As precondition you should read my guide “How to uninstall a system application on Zidoo Android 6/7.1 based devices“. It will show you how to root your device and how to use the Android Terminal Emulator.
Don’t install the modded APK directly eg. with ApkInstaller or you will end up with missing permissions!
execute Terminal Emulator
change from role user to superuser
change to Download directory
list directory content
use the package manager to install Home Theater
pm install -g zidoo_poster_4.0.8-McBluna-signed.apk