Go to Settings– > Accounts– > Access work or school choice (at the bottom)
Click Connect on top right
Since I’ve currently gone through the procedure, I can’t keep in mind if this alternative if prior to or after you go into the username/password of your organizational user that has worldwide admin advantages. I believe right after you click Connect, it will reveal a screen and at the bottom it will have the choice of “Connect to Azure Advertisement”. You may need to go into that user/password prior to or after that. The user to utilize here is the one you utilized to register to Microsoft 365 company with.
In my case, I had actually signed up with “jason”, and I had actually included a customized domain. If I were the user who signed up for Microsoft 365 with your domain, it would be “ firstname.lastname@example.org” and whatever your password is.