To access and contribute on a board as an anonymous user, you'll need to make sure that you're accessing the board without being logged on EasyRetro.
It's worth mentioning that you cannot join team boards as an anonymous user. This is only possible when accessing public boards.
Why? Because to access a team board, you'll need to be logged on EasyRetro. Plus, the creator of a team board has the ability to review the card's author.
To check if you are contributing as an anonymous user, here's what you can do:
1 - Check your profile name on the board
2 - Acess your profile page