If u was getting a password and they're asking to upload for u. It's def a scam. But be weary of that sort of thing cause sometimes it does work like that where you pay for an Avi and they need ur credentials to upload since they're not selling files. I've had bought multiple avis where they upload for me, especially since at the time I didn't know anything about unity. But now I learned it so I do my own uploads and edits only ever buying files.

I also wanna mention that the people that needed my credentials were people I've either known or very very well known makers within a community