@gurlcat every seller I know who does FB ads has a separate Business page, to keep their personal & business lives separate. I have never done it though b/c I believe FB is the devil & you couldn't pay me to use it, but lots of sellers do this. How much they think it helps, I have no idea. I had detailed instructions at one time from a forum I'm on but they are so old now that even if I could find it, I suspect it's changed radically. It is NOT the same as FB Marketplace & as @mcdougle4248 said, you do have to have an acct on the SM sites.
This one goes to Eleven - Nigel Tufnel
Simply-the-best-for-you Volunteer Community Mentor
eBay Seller since 1996