Short answer
HubSpot's KB: embed the scheduling widget so visitors book while on your site. Embedding on a HubSpot-hosted page needs Marketing Hub or Content Hub. For external pages, paste the embed code; some rich text editors modify the HTML comments in it, so check the code after pasting.
1. Meetings Scheduler
The meetings tool in my demo portal.

2. Height
The widget sits in an iframe. Give its container enough height so the calendar and form aren't clipped.