Hi - I am a brand new user and I have the most most simple question. I am trying to see how to add a smartapp in the Smartthings app and I see nowhere to add a SmartApp. What am I doing wrong? I use a Google Pixel 4a and just downloaded the app after buying an Aeotech Hub over the weekend.
Thank you.
Any smartapp in particular that you are trying to add?
the ST smartapps can be found in + Add Routine, click on the Discover tab near thetop and scroll down.
now, if you are trying to install a custom smartapp built by a developer, those are being phased out in less than a month.
myQ Chamberlain app to have access to my garage door in SmartThings app.
But it was just more of general question of how to see and add apps from within the app.
SmartThings is in the final stages of a migration from the old platform based on groovy to a new one based on LUA and Edge Drivers. MyQ is a custom smartapp that was written to run on the old platform and it will be phased out very soon. The developer is working a new version that could work with the new platform but it is not ready yet. I would not install the old version at this point but hold off and hope the developer is able to get it to work on the new platform.
You can keep track of his progress in the following thread:
Thank you for that reply, but can you guide me in general how to install any SmartApp or where to go in my app to do it?
I’m a level 0 user, brand new!
yes, I had edited my first post above while you were posting your response so details are there now 
basically tap on the + (in the upper right of the Screen) then select Add Routine, tap Discover tab near the top of the screen and scroll down… custom smartapps would be near the bottom of the screen. (yes - they put them in a really strange location)
Ok, I see those. Now how would I add any other SmartApp to this list? I’m sorry, I looked at the Wiki page and did not see a beginner level course on this funstionality.
if wanting to install the current version of MyQ… click on the link I posted above and there is a guide to walk you through the steps. But again, that smartapp will not be around much longer. for other smartapps, search the forum and check the first post where they generally have instructions on installing.
But again, I will try to discourage you from installing any custom smartapps at this point… you can but use of them will be short term.
I completely understand that, just playing around and trying to understand.
One more question - It says the easiest way to install is Community Installer. I think I installed that but where do I go to use it?
The community installer SmartApp no longer works. It would be in the same location that I posted but it would not work if you installed it.
All groovy smartapps which run in the SmartThings cloud will stop working in December, so most people aren’t spending any time on them these days.
Instead, people are learning how to use the new options: the routines built into the SmartThings app, the new Rules API (although that one has a steep learning curve), or using the third party app, SharpTools. SharpTools has a very nice visual interface, runs in any browser, and is more powerful than the basic rules engine built into the SmartThings app. It has a basic free tier and a more powerful pro option for $30/year.
Why don’t you take a look at the following thread, which discusses all of these options and more. Learning any one of those would probably be a better use of your time than working on something that’s going to be shut off in two months. 
You really do not want to even try. It will be wasted effort since all SmartApps are deprecated and will stop working in just a few weeks.
Many users equate the term ‘SmartApp’ with the Groovy SmartApps that were used in the legacy platform that is just being phased out. There were a number of ‘stock’ SmartApps provided by SmartThings, of which one of the most prominent was Smart Lighting. There were custom SmartApps that you could install in your SmartThings Location by writing or pasting code into the ‘IDE’ and publishing for your own use. Then there were third party hosted connected services, such as ActionTiles, where you would connect to SmartThings using an OAuth style connection and an app would be installed in your Location for you that acted as an intermediary.
Regardless of how they were created, the mobile app would handle them on the Automation tab. Apps that were available in your account could be added via an ‘Add SmartApp’ menu and would then appear in the SmartApps sections on the main tab, after Scenes and Automations (as they were then called). Then it got weird. The ‘Add SmartApp’ link was replaced and the available SmartApps were found by going to ‘Add Automation’ to open up a page of custom automations, hitting ‘Discover’ to switch to a page of automation templates, and then scrolling to the bottom. I have never seen an explanation offered for this. It then got worse because Automations were renamed to Routines. Automations was at least a generic term that also covered SmartApps (sometimes - SmartThings terminology is rather inconsistent) but Routines is specific to the basic ‘if … then’ automations managed in the mobile apps. That’s where we are now.
There are SmartApps in the current platform. There are SmartApps that can be used to integrate cloud connected devices which would appear when you go to add a device. There are SmartApps that appear on the Life page and so far are the closest we have to the legacy stock SmartApps. You will often see those called ‘Services’ instead. SmartApps can be used for connected services and appear as Linked Services on the app settings page. Then there is the nearest equivalent to the old custom Groovy SmartApps which are custom WebHook SmartApps. They are created and hosted outside of SmartThings and plumbed in via something called the Developer Workspace, and they appear on the Automations tab in the odd way described previously.
I recommend you visits https://developer-preview.smartthings.com/ to see how SmartThings goes together if you want to get beyond the point and click usage.