Hi Eric,
The Microsoft Account differs from the Office 365 account. They are two services provided by different Microsoft product teams. A Microsoft account is able to sign in to services like Outlook.com, OneDrive(SkyDrive), Windows Phone, or Xbox LIVE, but an Office 365 account cannot.
As a workaround, you’re able to associate your Office 365 email address with a Microsoft Account from this site:
https://signup.live.com/signup.aspx?lic=1
After doing it, your Office 365 email addresses will be regarded as a Microsoft Account. However, they’re still two accounts actually. For instance, if you change the Office 365 password from Office 365 portal, your Microsoft Account password will not be affected.
In addition, here is a similar post related to the usage of Microsoft Document Connection for Mac for your reference:
http://community.office365.com/en-us/forums/153/p/175143/513241.aspx#513241
Best regards,
Lawliet Xu