Roblox , can it be used to buy Apple apps

This person I know got a $15 Roblox gift certificate. She is trying to figure out how to redeem it to buy her daughters some app on their Apple iPads .
I googled it as I haven’t got a clue, but this gift card seems as though it’s dedicated to their own games on their own ecosystem ?
I have a feeling it isn’t going to happen

Sorry if this sounds like a dumb fking question,but I haven’t got a clue ,and have no idea how I get mixed up in this chit
Back with my Fam