What's the compatible android versions?

Maybe your phone doesn't support your app because it doesn't have enough RAM. RAM isn't the phone's main memory, but a certain place on the disk, which is occupied by the program only during its operation and then freed after the exit from the program. If this program is too powerful, it requires a powerful phone, while your old model can no longer do the job. Of course, it could also be an old version of Android. How long ago did you update your operating system? If I were you, I would look into the app's compatibility with my android version. If you don't have enough memory, you can temporarily delete all files to work with such a heavy program and then make ANDROID DATA RECOVERY. I'd do exactly like that.

It should be Android 8.0 and higher.

However, there are many, many different types of Android devices, and there is some specific hardware that may not be compatible with Unity, or a framework inside the SeeMusic app.

Without your specific device on hand to test, there isn't a way for me to figure out what could be going wrong.

I wish I could be of more help! I would recommend using SeeMusic on a Windows PC or Mac if at all possible.