To enable the admins/users to import their own PST files, the users must be given the “Mailbox Import Export” role.
This it how you configure / assign the users the role.
Login to the Microsoft 365 Admin Center and Open “Exchange” admin center.
Click “Permissions” > “Admin Roles” and “+” Add a new role
Enter details (example info), Add “Mailbox Import Export” role. Click Save
