According to the error message, ADFS is sending over the username "local\ad" and this user doesn't exist on your Tableau Server.
Is there a reason you are using a domain of "local"? Tableau Server uses local as the domain for it's local authentication identity store.
If your users are on one domain, and Tableau Server is on another domain, you'll also want to make sure the domains meet the trust requirements:
I'd recommend a few things:
For simplicity's sake, don't use "local" as your AD nickname.
Check the domain trust to makes sure it is set correctly.
Check to make sure the user in your error message actually exists on Tableau Server.
Contact Tableau Support for help.