Can't update: no tracked branch

If I'm not mislead, you just need to set your local branches to track their pairs in the origin server.

Using your command line, you can try

git checkout mybranch
git branch --set-upstream-to=origin/mybranch

That will configure something as an equivalent of your local branch in the server. I'll bet that Android Studio is complaining about the lack of that.

If someone knows how to do this using the GUI of that IDE, that would be interesting to read. :)

So after reading a bit on how git sets up the repo. I realized that I ran the command

git push origin master

but instead for the first time I should have ran

git push -u origin master

which sets up the upstream initially. Way to go!

I had the same problem when I transferred the ownership of my repository to another user, at first I tried to use git branch --set-upstream-to origin/master master but the terminal complained so after a little bit of looking around I used the following commands
git fetch
git branch --set-upstream-to origin/master master
git pull
and everything worked again