I have an upcoming planning committee that I want to use on Trello. I need to convince my team to use Trello but I have no way to access and impress the workspace.
Whenever I successfully logged in at the Atlassian start page, it asks me what I want to do? I, of course, have to head for Trello. Then the roadblock always begins within Trello's side: "[For] Two Factor Authentication: Use the app on your mobile device to generate a code."

It is a bane for more than 3 years now, longer because I don't use it during my transitional, period of moving upstate between Ohio Buckeye State and Michigan Go Blue. Only recently I found out Trello has been absorbed into Atlassian.
So that is the culprit. I recalled in the eve of the pandemic I logged in to Trello.com and mysterious it route me to Atlassian (I don't remember what happened next) but Trello Two-Factor Authentication Code had never been reset. Please disable that old Trello 2FA.
What is the difference between Atlassian and Trello 2FA?