Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
I have a solution for you (i googled it). In your screenshot i can see control panel in the background wich indicates you wanted to add new pst from there. And THAT is the problem. You can't.
Solution:
Open Outlook 2016
click file>account settings wich opens the exact SAME dialog as from control panel and from there you can add another PST..
Well done M$ :D