Hello,
First, I would like to confirm a few details to help narrow down the issue:
- Are you using Classic Outlook or New Outlook? (If possible, please share a screenshot of the Outlook window).
- Can you see the missing emails and folders in Outlook on the Web (OWA)?
- Did the issue start immediately after clicking "Next" in the Account Settings window, or was there a delay before the missing emails and folders were noticed?
- Are the folders showing the permission error located in your primary mailbox, or do they belong to a shared mailbox or another mailbox that has been added to Outlook?
In the meantime, please go through the checks below and let me know the results for further review.
1/ Check Outlook on the Web
- Sign in to Outlook on the Web: https://outlook.cloud.microsoft/
- Review a few folders where emails are reported missing.
- Check whether the missing emails and folders are visible.
-> If the emails are visible in Outlook on the Web, the mailbox content is still available, and the issue may be related to Outlook synchronization or local mailbox data.
2/ Check Recover Deleted Items
- Open the Deleted Items folder.
- Locate and open the Recover Deleted Items option.
- Review the list for emails from the affected time period.
Recover and restore deleted items in Outlook | Microsoft Support
3/ Review Exchange Cache Settings (Classic Outlook)
- Go to File > Account Settings > Account Settings.
- Select the Exchange account and choose Change.
- Confirm whether Cached Exchange Mode is enabled.
- Note the Mail to keep offline setting.
Turn on Cached Exchange Mode | Microsoft Support
About the error that you have mentioned, I found an Microsoft reference here:
Outlook error "Cannot move the items" when moving items to other folders | Microsoft Support

This will help determine whether Outlook is configured to download and display the full mailbox content.
I hope the information I provided will be helpful in supporting you to move forward with the issue you have been experiencing.
Kind regards,