@Liu, Michael, Thanks for posting in Q&A. From your description, it seems you have installed Intune company portal on MacOS to do the BYOD enrollment. But it seems the office 365 is unable to access. If there's any misunderstanding, feel free to let us know.
In fact, Microsoft Intune is a cloud service used to manage mobile device and apps.
For Office 365 access, it belongs to O365. Intune will not affect the access uncles you configure conditional access policy which needs the device to be compliant or require app protection policy to access office 365.
To check on this, I would like to confirm if any conditional access policy configured in your environment. And what is the error we get when login office 365 app. Meanwhile, please ensure the user has office 365 license assigned.
Please check the above information and if there's any update, feel free to let us know.
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