Is Siteground Security Optimizer Preventing me for having a new admin login?

Feeling so stuck and I really need your help. I tried adding a new admin to my back office today and they keep getting “error – the password is incorrect.” or the “Login info is incorrect.” Adding a user is a pretty simple thing….usually….BUT over the summer I did add Siteground Security Optimizer and I am wondering if this could be the problem? When I went Siteground Security Optimizer in my wordpress and go under Login Security – I notice that we turned on Two-factor Authentication for Admin & Editors Users, BUT this new user I was trying to add through the back office is not listed. Also this new admin didn’t get any pop-ups or anything about adding the two-factor. SO is this 2-factor info something that I need to be providing this new Admin as well? I am feeling so stumped on how to log this new admin in! Any help you can give on what I need to do here would be so greatly appreciated! You would be my hero!