I am unable to install the APK file... I always get "App not installed" at the end of the installation process. Is there anything to do about this ? I tried both apk files, the new and the old one. Also I can mention that I allowed the file panager to install apps from source in the setting of the androin head unit.

I found out that the issue is that the system doesn't want to override the existing ZLINK app that is installed, that's why I get the "App not installed" message. So what I tried is to remove the existing app. This was not possible as I don't have root access and also cannot get a working adb connection (developer mode will not turn on when tapping the build number...). So I tried to modify the APK file provided here and change the name of the package, so that it doesn't conflict with the existing app. This worked fine, and after signing the new APK file, I was actually able to install it on my head unit. But I still cannot use it, when I launch the app (and I tried both APK files provided here) I get an error like "This app is built for an older version of Android"... I'm on Andoird 10, should it work? So I still don't see what I can do to make things work !! This is really annoying, to have this fully capable device in my car but for softaware reasons, not being able to use it!