A lot of people don't understand the difference berween a google play link and an apk link
The google play link is the quickest way to find info on the game (current version etc) and to easily install the original version if it is needed.
The APK link is what the modder needs to download the apk that will be decompiled in order to mod.
Not providing an apk link shows you expect the modder to chase around after you before they can even mod the game.
There are plenty of sites around that will fetch a google play link and give you a download link one of the popular ones is