Hey, and welcome.
When you would download an app:
Search the app and tap on the picture or the app name + mod under the Pic.
Then scroll down, you must tap there on Mod.
The next side shows you the short description from the app. You must wait until the words Proceed shows over the description. Tap on it.
At the next side you scroll down to found "show for xxx SB"
Spend the SB Points and you can download the MOD.
Sometimes you must tap on proceed twice.