Hi Carol -
The current version requires all users who want to use the O365 integrations to login via AAD using the OpenID Connect authentication plug-in. You can connect your existing users to the O365 authentication, but this will switch their authentication method to OpenID Connect.
We are working on new features currently that will simplify the entire process, and allow users to maintain the existing authentication methods they are using, while connecting their account to the O365 system. These should be ready in 3-6 weeks.
mike