You need to properly configure the AppAPI
Once you make it so that the Default Deploy Daemon is accessible then you will see that the ExApps are no longer greyed out.
When you find the proper settings to get it working please report back here. I have gotten as far as Nextcloud pulling and creating the containers and volumes in docker when hitting the “Deploy and Enable” button but there is something wrong with my config where Nextcloud does not recognize that it is running and communicate with the running container?