They allow mobile check-in, but you need to go to the kiosk for keys. They don’t do mobile keys, as far as I know. And, the kiosk requires an ID. It can be either a passport or drivers license, so you could just send along your passport with them if you don’t need it. I haven’t actually stayed at the Planet Hollywood for years, but this has been my experience at the Flamingo, Horseshoe, and Paris.