The Game Changer Program?

Hello. I'm a Polish Sims youtuber with 15,000 subscribers (still growing) and I'd like to get some information on how the Game Changer program works. I mean getting free packs for Sims 4 to review/show them in a video. I'm not saying I'd like to become one right away, or maybe even at all, I'd just like to find out how it works exactly, as people are constantly telling me a thing like that could be available for me at this point. Could someone give me some first-hand details?
Thanks in advance!