...hang on... Maybe I'm being a bit thick here but what your posts suggest is that as a box-fresh C0 class drone: the mini 5 pro is limited to 400' altitude unless registered with DJI as a >250grm C1 class drone which increases its ceiling to...
Interesting... I'm reminded of the geo zone map function that started out the same way: optional and for reference only to begin with, then at the press of a button in DJI H.Q: became mandatory.
This may tie in with the (near) future requirement...
DJI Vision is the correct app for the P2 Vision.
But it is an old app, maybe it is not fully compatible with new Android OS. Try to find an old phone with older OS, and see if it works.
Try downloading the app directly to your phone from DJI...