Complete a survey and get TikTok coins or whatever, you would not get anything as promised after completing the survey(s). However the affiliate marketeer behind the survey(s) gets paid for the surveys you would complete. It is not an outright scam, because in a mere survey you did not spend any money, perhaps only some time, so it is a greyhat area. The emails and data collected through the surveys are used further as a funnel for affiliate marketing.
By the way, welcome to the world of affiliate marketing (many of us have atleast once earned from content lockers, along our journey). Reverse engineer to learn the mechanics to be a part of the side that profits).