How can I make scheduling form that will populate a calendar?

Hi @juliawatson,

You can try our Date Reservation widget if it satisfies the requirement. 

This widget allows you to display a calendar on your form which your users can select dates that correspond with the purpose of the form. If prior form users have selected a date or a range of dates, they will be grayed out - they cannot be selected.

Here's a demo form for you to try: 92486041306959

Aside from that, you can also try integrating your form with Google Calendar. Please refer to this guide about Google-calendar-integration.