[ES] Is this type of “paid promotion” real or just a scam?

I recently got a DM. The brand (their name is “vervest”) told me that after a certain number of sales I could earn free unreleased items and even cash bonuses. They also asked me to post 1–2 times per week wearing their clothes and tagging them, usually for a period of 1–4 weeks.

They gave me a “password” to enter their website and said I’d need to buy something in order to get my own code.

My question is: how legit are these kinds of “ambassador” or “influencer” offers? Can I really trust this type of advertising deal, or is it usually just a scam to make me buy their products?

How safe can I be if I join something like this?