Hi @IBN
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For getting access to Teams, a user must have an assigned Microsoft Teams license from Office 365 Admin Center. Because without assign Microsoft Teams license users cannot log in to Teams.
If you are the admin, you could try to follow these steps to assign the license for this user:
- Go to admin.microsoft.com page.
- Click the Users drop-down button.
- Select the Active Users option.
- Choose the user.
- Click the More Actions button.
- Select the Manage Product Licenses option.
- When a new window pops up, scroll down to the Apps section.
- Check the Microsoft Teams option.
- Save the changes.
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