WHMCS MU Provisioning Plugin not Creating Accounts Automatically

I've got the plugin mostly configured (it seems), but I am facing two deal-breaking issues at the moment.

1) Accounts are being configured in WHMCS without admin intervention, however, Wordpress accounts must be "created" manually via client-view.

2) I have tried a few different domain variants in the "Default Blog Domain" but no matter what data I input, I receive the following error upon manual account creation:

Module Command Error
Site already exists.:

Any suggestions would be greatly appreciated. Thanks! : )

PS FWIW I have disabled all other plugins, but using non-default theme (iThemes Builder Child Theme).