If App Crashes on Start up:
Enable Permissions for Storage & Phone
If App is in a White screen:
Clear Cache and force stop the app.
If App is detected as Unauthorized or modified:
Force Close the game!
Clear Cache, Force stop and if it's still not working unallow all permissions and reallow.
If app isn't downloading:
Make sure to install
SIGNED: If you don't have rooted device. If you don't know what root is you probably don't have root so install this one.
UNSIGNED: If you have root + LuckPatch Patchers installed.
If you don't know if you have root or not, most likely you don't have root.
(Thanks to @Anitakawaii for sharing his/her experience)
Looks like the apk is broken:
DRAGON_BALL_LEGENDS_EN_v4.23.0__unsigned__FREE_MOD_Menu_by_Yeowang__platinmods.com.apk: Failure [INSTALL_PARSE_FAILED_UNEXPECTED_EXCEPTION: Failed reading stamp-cert-sha256 in android.util.jar.StrictJarFile@f8dc176: META-INF/MANIFEST.MF has invalid digest for stamp-cert-sha256 in stamp-cert-sha256]