For a correct use you need :
Kustom (KLWP PRO) https://play.google.com/store/apps/details?id=org.kustom.wallpaper.pro
A KLWP compatible launcher (NOVA LAUNCHER RECOMMENDED)


How to use themes:


1. Install KLWP
2. Open our app
3. Tap on the preset you want to use
4. Tap the "save" icon in the top right corner
5. Go to your launcher setting
6. Set the exact number of screens I mentioned at the beginning of this app's description next to the name of the preset you're using


This is a big collection of our theme in free download and for our happiness

Credit for KLWP preset to ChrisPro00 on reddit follow it for more preset:
https://www.reddit.com/user/ChrisPro00