Error: cause: compileSdkVersion is not specified

Greetings !!
I have downloaded jitsi-meet project from github and opened in android studio.
Now,I’m getting another error “cause: compileSdkVersion is not specified” while its metioned in gradle file- compileSdkVersion=28

and thinking how to resolve this??

Kindly ack. and guide if i am on the right track to the resolution.

Before moving to Android studio, did you successfully build it from command line, as explained in the readme file?