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: