re: green dot, no “SkipHill” found in members roster; cursory glance @ WHMCS doesn’t find any members with names like “skip hill”.
I know we have had some growing pains with the calendar system, and Team_Infra is actively working on it generically; to get help for this specific individual may require specifics about this experience, and the ticketing system is friendlier way to pass personal details.
So I’ll suggest @SkipHill mail accounts at dallasmakerspace dot org where we’ll ask for some details (though some may be furnished by the ticketing system if it’s able to match up the inbound email with a member account) such as username, screenshot of the actual web site URL and filled in username field, along with another screenshot of the actual error message (this may be what has already been posted).
Meanwhile, I’ll suggest reaching out to the instructor. Mention the difficulties getting signed up, and ask if you can attend despite this setback. Often they will say yes, but we do have to respect their decision as they are responsible for maintaining an attendee count and classroom environment for the safety and comfort of all.