Install App as system with modify.phone.state permission

Hello guys

i'm trying install app third party app im my phone, but not working

i rooting my device and add MODIFY.PHONE.STATE permission and put android:sharedUserId="android.uid.system" but not working

if i remove the permission and shared user the app install in system folder, other hand don't

someone have any idea how install this app with MODIFY.PHONE.STATE permission