Microsoft Office Outlook cannot access the specified folder
The error is because permissions are not assigned to the user.
There can be more than one solution to resolve this error:
Solution 1: Login to Office 365 using the Administrator account.
1) Go to the Office 365 admin center users and groups, search for Manager email account
2) Once you find your Manager's email account, Click the link to view the details
3) click on 'More', Click 'Edit Exchange Properties' to load to the next page
4) Click 'Mailbox delegation', Select 'Full Access'
5) Click 'OK'
6) Click 'Save'
Solution 2: Manager's MS Outlook
1) Open 'MS Office' program
2) Click on File, Info, Account Settings, then Click 'Account Settings'
3) In 'Account settings', Email Account, Click 'Change More settings'
4) In Microsoft Exchange, Click 'Advance'. Click 'Apply'