Sorry to hear that, I'll try to reproduce the error and see if I can figure out what's causing it.
1 year ago(+1)
Okay, after reading the other comment I also gave it another try.
The error message in sidequest was: "A task failed. Check the tasks screen for more info. PolyWaiter.apk: /data/local/tmp/_stream.apk could not be installed [INSTALL_FAILED_UPDATE_INCOMPATIBLE: Package com.UnityTechnologies.com.unity.template.urpblank signatures do not match previously installed version; ignoring!]"
I googled and found the solution on SO. Just need to run following command (to run the command use the top right button in sidequest ):
adb uninstall com.UnityTechnologies.com.unity.template.urpblank
After that I managed to install the game.
Maybe the issue is you used development build?.. At least they say on SO it can be the reason.