Open the Microsoft 365 admin center and go to the "Admin centers" section.
Click on "Exchange" to open the Exchange admin center.
In the Exchange admin center, click on "Permissions" in the left-hand menu and select "Admin roles" from the drop-down menu.
Click on the plus (+) icon to create a new role group.
Give the role group a name, such as "PST Importers," and add the users who will be importing PST files.
Click on "Add" to add the "Mailbox Import Export" role to the role group.
Click on "Save" to create the role group.
Next, you'll need to create a new import job. In the Exchange admin center, click on "Recipients" in the left-hand menu and select "Migration" from the drop-down menu.
Click on the plus (+) icon to create a new migration batch.
Select "Import PST files" and click on "Next."
Enter a name for the migration batch and select the mailboxes you want to import PST files to.
Click on "Next" and then select the "New" button to create a new Azure Storage account. This is where you will upload your PST files.
Enter the required information for the Azure Storage account and click on "Save."
After creating the Azure Storage account, select it and then click on "Next."
Enter the path to the PST files you want to import and select the options for the import job.
Click on "New" to create the import job.
Once the import job is created, you can monitor its progress in the "Migration" section of the Exchange admin center.