how can I play fortnite through the xbox pc app?

they are only allowed to provide access via the browser version of cloud.

How, Through the xbox app. I tried and can only find a way to play your Xbox on the PC

no as you have to get vbucks via ingame or through the epic store on pc, fortnite on pc has nothing to do with microsoft or xbox.

you can redeem on pc via xbox app or store but to access them you need to be on xbox console version of the game.

Hello Dancing,

Thanks for coming to the forums with your question. You can download Fortnite on the Xbox app on the PC and play there, or there is a pc version also that will allow you to play. You then can play with your son on Fortnite as long as cross play is enabled
on the Xbox. Also make sure to add each other as epic friends and can invite from there too.

Hope this helps.

Thanks,

Brad

if it was redeemed via microsoft store or xbox app then you need to load fortnite on an xbox console or via xcloud for it to sync to your epic account, if you play on pc then all future purchases are better done in game or through epic store.