So I'm guessing you dont have enough RAM and you are on limited data plan(no wifi)
I get it. But Ren'py games are not the issue. it's the renders(animations, pictures) and some audio can also get in the way if you have low RAM. so yeah, Ren'py is basically just the code which is usually barely 1mb. an then the renders, pictures, audio are the big stuff. those renders are made with different software like Daz studio or Honey select 2 or even blender.