What is a one-time password? Can't access my Square Enix account

I signed up to a SE account some time ago, it was the only time I logged in their account system. When I tried accessing it again yesterday to pre-order a game from their store it asked me to login with my SE account, which requires 2 passwords? I'm sure I signed up with 1 password, I even

Frequently Asked Questions

One Time Password (OTP) How-To

SQUARE ENIX Support Center - SQUARE ENIX Account

SQUARE ENIX Software Token - Apps on Google Play

SQUARE ENIX Support Center - FINAL FANTASY XI

SQUARE ENIX Software Token - Apps on Google Play

Getting Started, Game Manual

SQUARE ENIX The Official SQUARE ENIX Website

Security Token Email : r/ffxiv

Square Enix NA Support (@SE_NA_Support) / X

SQUARE ENIX Support Center - FINAL FANTASY XI