I'm having a lot of trouble with this, it's been a few days.
I have successfully tested google maps on my simulator, but also on my personal device without any issues, everything was working perfectly. However, once i uploaded it to the store for internal testing, my testers are not able to see the map.
After some research, it seemed that the reason causing this problem was that I was using my debug certificate instead of my release certificate on my Google Cloud Platform. I changed the SHA-1 certificate on my existing API and now the map is not showing on neither my personal device (through Android Studio) nor my tester's devices - it is only working on my simulator.
Am I missing something? Should I have tried to create a new API instead of modifying the existing one? Does any of this can be related to the "OAuth consent screen" which I'm not familiar with at all?
Thanks for your help, any feedback would be really appreciated.