Sometimes Tableau requires sign-in to display reports within monday.com. The solution depends on which platform you are using.
Safari Users
If Tableau displays the sign-in screen and after signing in there is no update to the above screen:

Follow the guidance in Some of my Safari users cannot see the content in an app.
monday.com Desktop App Users
The desktop application cannot open sign-in screens in new windows or tabs, preventing report access.

Solution: View monday.com in a desktop browser instead.
monday.com Mobile App Users
The mobile app cannot open authentication windows, blocking report viewing.

Solution: View monday.com in a desktop browser instead.