If you want to allow people to register for class without paying. For example, maybe when they are leaving for the Summer, but you want them to go ahead and add themselves to a class, here are the important settings. They are outlined in the video, or see the additional detail below.

First, for any classes that you want to offer this way (no payment), make sure under the class settings, you have enabled Billing Schedule as the payment method, and the class registration fee (for this class only) is set to $0.

Next, under Settings > Online Client, in the Classes sections you should have them set like this:

Then below this section, you can also decide if you want them to actually be put in the class, or just added to the waiting list. If they are added to the waiting list it means the class can’t fill up (ex. as the new season is approaching you want people who paid to have priority). Here is an image of that setting, and you can decide whether you want Waiting or In Class this way.