cannot open Shared Mailbox directly via OWA

Hello Community,

i got a problem that i cannot open directly a Shared Mailbox.

That mean i go the Browser, tip in the Shared Mailbox Credentials and cannot get in.

I can go over my User Profil and then on the OWA, but this are one Step more to go.

How can i make this possible, via Shell or Exchange Admin Center?

Thanks a lot!

Kind Regards.