If SAML single sign-on is activated but you can’t provision a user due to this error, it typically indicates that the user has not been granted access to Grammarly in your identity provider.
To resolve this issue, make sure that the Grammarly application is assigned to this specific user or that they belong to the appropriate group in your identity provider with access to Grammarly.
If you’re using SCIM provisioning, we recommend checking the identity provider provisioning logs for any errors and verifying the status of this user.
If all of the above are correct and there are no issues, try revoking access to Grammarly for this user and then reassigning it to them again.
For more information on SCM provisioning, please refer to this article: Configure SCIM provisioning