This also means that you are required to have the Toolset Forms Commerce plugin installed. Please let me know if you're having any issues at all or on which step of our documentation on this that you are unsure of.
I'm not sure where exactly you are referring to because the exact link that i've sent shows how to setup the form to charge the payments.
The payments are charged when the form is submitted on the frontend, as well as the product is used to setup the payment for the form.
Can you provide me with access to the site so that I can have a look at what you've already done ? Also send me a link to the page where you have the form setup on the frontend so that i can go through and see what has been done.