Hi Timothy,
I appreciate your further clarification and sorry for my mistake. For the first issue, now I understand that it is related to the OneNote client. To ensure you get the dedicated support, please post it in our OneNote forum. Thanks for your understanding.
For the second issue "Outlook/OneNote cannot verify 365 subscription", I'd like to collect some information for further investigation：
1. Is your organization using ADFS to provide web single sign on (SSO)? You may find it on the page below when signing into your Office 365.
2. Could you share a screenshot about the error message with us?
To upload screenshots, you can click Use rich formatting in the forum and then click the icon of Insert/Edit Media.
3. To exclude the effect of the Mac client, if it is convenient, would you try it in a different network environment or another Mac?
Please post back at your convenience. We will help you further.
Best Regards,
Jim