Bro you can't install directly. Magisk must be installed on your device and you must have root access rights. Then you have to use root explorer.
- Copy downloaded mod camera file to /system/priv-app/MiuiCamera/MiuiCamera.apk.
- You should set permissions 0644.
- Clear cache&data camera apk...
Everyone's so many different requests, but I can share a link to modded camera files.
*Don't forget to set permissions after copying the new camera file.
*Settings/Apps/Manage Apps/Camera -> Clear data -> Clear all data