The download never finishes
Stay on one connection until the file is 2,052,113 bytes. Delete a partial file before you retry. Start from Download on this preview, not from a mirror.
Parse error, or the app was not installed
Android is saying the file is not a package it can read. A file that stopped early, an HTML page saved as .apk, or a download that is not 2,052,113 bytes will do this. Delete it. Hash a fresh copy if you can. The value is on Verify.
The install is blocked
Android is waiting for you to allow installs from the app that saved the file. Allow that source for this file, then return to the file and install it. This page does not tell you to turn Play Protect off. If the warning is about a file whose size you did not check, deny it.
A different package is already installed
come.apk will not replace a package other than app.rs9.come. If the phone refuses, read the package name before you delete anything. A different signature on the same package name will also be refused.
It installed, then it will not open
Confirm the label is COME and the version is 1.0.0. Free space and a finished download come before a second APK from search.
The icon is there, and the package is different
App info is the check. If the package is not app.rs9.come, the icon is a different app. Do not treat that icon as this file.