was it one of those hacks who pretended to be "Admin"?
I dodged this scam hack long ago, as I didn't gave him any personal info.

you guessed right

Have you heard the teaching: The staff/admin will never ask for your login name and password?

Because I was following scam hackers guidance just like you, until he told me to discover that info, so then I immediately understood it's a scam

It may be too late, but I think it's worth to share what scam types there can be on steam https://www.reddit.com/r/Steam/wiki/scamtypes