I've been trying to get them since Twitch Prime rewards GTA and RDR2, but for some reason I never get anything in games. It even says that I would have picked it up. I searched for solutions for months and checked everything several times. Apparently I'm not the only one. In a WhatsApp I'm in, someone sent a picture that it now works for him, but didn't want to tell anyone how, so there has to be a way.
You have to connect your Rockstar games account to Twitch, otherwise you won't get anything, that's the case with every game.
I've already done it, they are the right accounts, but I didn't get one of the Twitch Prime packages, although according to Twitch Prime I picked them all up.
Happens.
