Okay, so with Steam Authenticator, what I had to do was go to my security settings on mobile, and click on "add authenticator" or something like that. It asked for a phone number I believe, and I put my Apple phone number. It sent a verification code or something (sorry I can't really remember too much, I enabled it quite a bit ago) by text, and I would do something with that verification thing which would enable it. Sorry I can't really remember in detail, but I hope I could help you somewhat. Remember that once it's enabled, every time you sign into steam, it will ask for a authenticator code. This code will be available in the "Steam Guard" tab once enabled, and a code will appear there. You may also get a notification telling you the code. Not sure it's the same for all devices, I use a samsung for my steam app, so sorry if it differs.

Hope it helps you out, glad to help.

everyone ima bout to improve my username to change ok please dont miss the username whenever i do it ok i will redo it
gl everyone

hi

+rep cute

yea

Is somewhat a nice friend and good player +rep