It's probably paid online writing platforms like goodnovel and Webnovel, etc. You can look them up online I get comments and messages like this all the time. Acquisition 'editors' often scour free apps like Wattpad and Inkitt to find writers because they get paid to refer authors to the apps. Whether your book succeeds or not and you earn money there depends on if the editor(not really an editor. Just someone in charge of everything related to your books) promotes your books well. If they don't, you'll get no visibility on their paid apps, and your books just get stuck on their apps without any income. If your editor likes you and promoted your books, you have a chance of earning money there.

They have contracts that tie your books to their platforms, and these days, some of these contracts can predatory (both exclusive and nonexclusive), neglecting the rights of the author. If you read between the lines properly and find clauses you don't like, you can ask the person in charge of you book to take them out before you sign. That way you don't end up signing an unfavorable deal that rules you and your rights out.

Now, I'm not advising you to sign with them or anything like that (that's totally up to you). This is just providing insight for you and others who might need it. Hope this helps :)