Cannot get Scheduler to work

I am trying out the free plugin prior to moving to the pro upgrade, and think I’ve configured it properly.

To test it, I logged out of WP and went back into the scheduling page of the site, pretending I am a client. It allowed me to select the appointment date and time just fine, but whenever I click on any of the phone number, name, comment and captcha fields below, I automatically get kicked over to a Word Press login screen.

What could be causing this plugin to malfunction like this? I’ve deactivated all other plugins except for the Go Daddy Set-up and WP SEO plugins.

Thanks in advance for your assistance.

https://wordpress.org/plugins/appointment-scheduler/