Thanks for reaching out to Jotform Support. I checked your account and I see that you don't have a form. I guess you mean the form picker menu showing loading. If so the reason is you don't have form. Let me show you how Quiz Form works:
Go to the Quiz Form page and click on Open Quiz Form.
In the pop-up window click on Allow.
In the Form Picker menu select your form and click on Continue.
In the opening page, select your options according to your need.
Select correct answers in the form and click on Save Quiz.
Open your form from the My Forms page and in the orange navigation bar at the top of the screen click on Publish.
Share your form by using the URL or invite people through their email using the Invite section.