Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
You don't import pst files.
(Courtesy of Russ Valentine [MVP-Outlook])
Importing an entire PST may well corrupt your profile and may create a ghost
PST that you can't close. Importing PST's will lose:
1. Custom Forms
2. Custom Views
3. Connections between contacts and activities
4. Received dates on mail
5. Birthdays and anniversaries in calendar
6. Journal connections
7. Distribution Lists
Opening a PST file will preserve all of these. That is why we do not advise
people to import a native file into Outlook.
Copy the pst file(s) to your Documents folder (do NOT overwrite any existing pst files, or paste them in the default Outlook pst location).
Then in Outlook do File-Open-Open Outlook Data File and navigate to where you put them.