@Sarah Bunting, Thanks for posting in Q&A. From the error message, it seems we register or join into Microsoft Entra and enroll into Intune. But it seems the device management is not enabled and is failed. If there's any misunderstanding, feel free to let us know.
To fix this, please ensure the account we sign in has both Microsoft Entra Premium license and Microsoft Intune Plan 1 license assigned. Meanwhile, please ensure the MDM user scope is set ALL which enable automatic enrollment.
https://learn.microsoft.com/en-us/mem/intune/enrollment/quickstart-setup-auto-enrollment
Please try the above suggestion and if there's any update, feel free to let us know.
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