Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Dear mohammad qablawi,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
This error occurs when you assign a similar license to the same user, depending on your problem and the error information that you provided. According to the error message, the user already has Exchange Online (Plan 1), so you can't assign Exchange online kiosk to the user until you remove the Exchange Online (Plan 1) license in the admin center.
Therefore, please kindly ask an administrator within your organization for help signing in to the Office 365 admin center with an administrator account, in the user's Licenses and apps section, expand Apps, uncheck Exchange Online (Plan 1), and then see if Exchange Online kiosk can be assigned to this user.
Sincerely,
Kerry Chen | Microsoft Community Moderator
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