Hi Barbara Hernandez,
Welcome to our forum!
The error message "UserHasNoMailboxAndNoLicenseAssignedError" indicates that this is a license issue. It could be that the admin has not assigned an Exchange online license to your account yet.
Please refer to this article: https://answers.microsoft.com/en-us/msoffice/forum/all/something-went-wrong-we-couldnt-find-a-mailbox-for/6480660c-db0d-4c2f-b04d-9e01ab2a4f3d
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