Hi Chris,
Thank you for contacting us here at Method. I know you spoke with Val, but I wanted to forward the resolution to issue so that everyone can take notes.
If you have a scenario where a user is unable to log-in to the Method plugin that you created in Method under customize -> users, kindly ensure that you enable the This user is allowed to connect to Method API option, as this is what will enable the user's Outlook plugin to connect to Method.
By default this option is enabled for the administrator of the account, however you have to enable this option manually for each additional user you create that you want to be able to use the Method Outlook plugin.
I hope this clears up some of the confusion.
Regards
Denis