This notification indicates that your organization allows the use of work email addresses only for accounts that are part of its Grammarly subscription.
If you want to continue using your Grammarly account individually, change your email address by following the steps in this article: I need to change my email address
To join your organization’s Grammarly subscription using your work email address, please sign in to Grammarly through your organization’s identity provider, such as Okta, Microsoft Entra ID, Google, or another.