APK Validation Failed

i will try as i had issues also.

on Project settings :
- choose min max 21 , also on NDK -21 and latest
- on storage choose AUTO
-make sure you are on SHIPPING and DISTRIBUTION
-make sure you choose START IN VR ( search it on general settings i think, on bottom)
-Check the box that says something like configure for Oculus GO
- make sure you made a KEY for android distribution, and copy it on projectname/build/android/

Package : 
-package on ASTC , for arm7 + OpenGL ES 2

NOTE:
Take your time reading oculus docs for ue4, sure they miss same stuff but for most parts its a very good guide!

And try submitting again! :-)