I would like to configure Smartthings devices on the Openhab system, to do this the system asks me to add a “SmartApp” from the “Smartthings Developer” site. If I go to the “My SmartApps” page I don’t have the possibility to create one. Also, I noticed that on the “My Hubs” page, I don’t see any Hubs, and the message suggests me to elect a device from the mobile application as a Hub, but I don’t see this option in the application. Can anyone tell me how to proceed. Thank you
SmartThings is in the middle of a huge architecture transition and SmartApps will no longer run in a groovy cloud hosted by Samsung. Instead, you have to host them yourself and connect through the new REST API. So there’s a lot of stuff out on other sites now which is out of date and will no longer work.
There is discussion of this in the openhab forum, but so far no one has an alternative for the new architecture that I’ve seen (the topic title is a clickable link.):
There are some options under the new architecture if you want to use MQTT to bind the two systems together, but that would be a lot more work than the old method. I think you’ll probably get the best information going forward from the folks in the openhab forum.
Thanks, I’ll go read the thread.
In the meantime, I tried to buy on Amazon: “Aeotec GP-AEOHUBV3EU”, a SmartThings hub and let’s see if I can pair the fridge and create a SmartApps.
Adding a smartthings/Aeotec hub will unfortunately not change anything with regard to Smartapps under the new architecture. You still won’t be able to add them. 
In the old architecture, smart apps, ran in the free cloud provided by Samsung.
In the new architecture, “edge drivers” which allow direct communication zigbee or zwave devices and the hub do mostly run on the hub. But smartapps do not. We as customers are not allowed to add smartapps to a smartthings/Aeotec hub.
Instead, you have to host the smartapp yourself either in a cloud service, or on a local server device, and then communicate to the smartthings cloud over the Internet.
So having a hub does not change the options you have for smartapps.
However, having a hub would then give you the option to use MQTT for some external integrations. I don’t know if that helps with openhab or not, though. 
Again, I would suggest talking to people in the openhab forum to see what plans they have for future smartthings integration under the new architecture.