[Account Manager Email] is Current User

You'll have to compare email to email or user to user. So that could look like:

ToUser([Account manager Email]) = User() 
or
[Account manager Email] = UsertoEmail(User())

You can either use a Report Formula for this, or you can create a new formula checkbox field called [Account Manager is Current User?] , with either of the formulas I put above. Then in your report, use that checkbox in your filters.

You're on the right track but you're comparing a username to an email which won't match. Use the user field to capture the correct user or match with email instead of the username.