Here are steps you need to take in Appointment Type so that web conferencing link is added in calendar invite when meeting gets scheduling using this appointment type:

Step 1: Go to "Appointment Booking"

Step 2: Click on "Manage Appointment Types" on a Booking Page of your choice.

Step 3: Click on "Edit Appointment Type" on an Appointment Type

Step 4: Navigate to location.

Step 5: Your web confernecing service would have been listed. Go ahead and select it.

Step 6: Click on "Save Appointment Type" and go back.

If you don't see your desired web conferencing service listed click on link below and find your web conferencing service to link and click on "Add".

Click here to : Link a web conferencing service