@mateo_salta was realy kind and helped me out. The issue was as far as I can tell that the clickable framework was not set properly.
After running the CLICKABLE_FRAMEWORK=ubuntu-sdk-20.04 clickable --arch=all command and updating the apparmor file to 20.04, it now works !

Hi,

I have just installed clickable and am trying to build an app. For some reason the clickable desktop command works but the chain does not. Everything works until installing the app

Installing the app.
Transaction:	Installing files
Status: 	Waiting in queue
Status: 	Finished
Results:
Fatal error: No such file /home/phablet/test.test_1.0.0_all.click, or unknown or unsupported content type

Cleaning up.

Running command "launch"
Trying to kill the app before starting

Launching app.
bash: ubuntu-app-launch: command not found

Any idea on what I should do to fix this is greatly appreciated.