Can`t open PSB File with Photoshop 2020

[Ixvakel]

Urgent help needed! Can`t open a PSB file with Photoshop.

It says there is no program installed to open the file. If I search for Photoshop manually to open the file, the open button is greyed out. No chance to open it. 

Screenshots attached. (German language)
I have the new Photoshop 2020 and a new MacBook Pro (16 inch, 2019)

[Test Screen Name]

Please start Photoshop and use Open from the File menu. What happens?