You can use Signup Sheet to do this. Using which you can host webinar, group interviews, group study sessions etc. Once people book a slot, they receive calendar invite for the meeting.

Step 1: Go to Appointment Booking Page and Click "Manage Appointment Types" on Booking Page of your choice.

Step 2: Click on "New Appointment Type" and select "Manual" in how to set available times for meeting

Step 3: Click on "Edit Appointment Type"  and navigate to section 2 to change duration. Select the duration of your event from there. You can also go to section 3 and change location if you would like.

Step 4: Click "Save Appointment Type" and go back.

Step 5: Click on "Change hours" on this signup sheet.

Step 6: Click on "Change Times".

Step 7: Add times

Make sure you click on "Done" and then "Save" after you update your timeslots.

Step 8: Update capacity: maximum number of people who can reserve a single time.

Say you are hosting a webinar and can accommodate up to 200 people. You update capacity to 200. Once 200 people have signed up for the spot, we will remove the timeslot for the booking page.

Step 9: Save and Go Back.

Once someone signup, you will receive an email notification and you will also be able to see their reservation for that time on Calendar page in FreeBusy.