Why can't I add custom themes?

[unnamed.norwegian]

I just wanted to install Pixel Ultra theme... but I can't because of this frickin rom which is called miui. Some poeple may ask why didn't I just install PixelExperience... well its because mobile data works only when i have miui. So can anyone please tell me how do i do it?

 

[MeowMilev]

guess that APK needs to update properly to run on Miui14. i have a long list of apps not installing properly on MIUI14 compared to ONE UI which compatible with a lot of apks. in summary, don't buy Mi as your next phone! I know i Won't!