Me and a friend of mine wanted to play something today and since fortnite is free, we wanted to play it. I downloaded it to my PC and unfortunately she only has her cell phone or tablet available. Can we play trzd together if she downloads it to her tablet or mobile phone?
It depends on whether you can download it at all
Does she have Android or Apple?
Yes. Forntite supports all kinds of cross play and cross save things. But she has to be able to download it first. At Apple it doesn't work anymore. Mobile phones and tablets are never supported.