Ok, here are my 2ct on how I got v4a working.
My device: Mi 9 EE
v4a version: 2.7.1 (available on xda)
Installing by using the apk.
rooted with magisk (20.0)
In my case, it was selinux, which was preventing the driver installation.
1. Get some terminal emulator from store (i used material terminal)
2. open the terminal emulator
3. type: "su" (to gain root access)
4. type: "setenforce 0" (to set selinux to permissive)
5. type: "getenforce" (to ensure selinux is now set to permissive)
6. run the v4a v2.7.1 installer.
7. open v4a. It will ask to install the driver. Yes, let v4a install the driver and reboot.
8. after the reboot check the v4a status and report please