Hi,
Are you in Exchange cached mode? If this is the case, the try to switch to online mode, and verify result again.
If you can see all the sub-folders in online mode, then it might be due to the number of folders and the number of messages, not a permissions issue.
In Exchange cached mode, tick the option of "Download shared folders" under Account Settings>Change...>More Settings...>Advanced tab. After this, restart Outlook client, then test it again.

Regards,
Ethan Hua
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