Tracking custom goals that are not on my website
This is my first question on Optimizely Community and I'm not sure this is the right forum so if not, please tell me so I can post it on or migrate it to the right place.
We offer a 1-on-1 call in my company and in order to book a demo, a user needs to pick a date in a third-party calendar from calendly.com. Once the user signs up for a demo, our analytics tools identify them as a new booked lead.
Now, we want to test our VIP demo page but we can't use the page view goal because there is no page redirect after they register and we can't even use a custom goal because the lead is obtained on calendly.com. So I'm trying to find solutions for this, if anyone can help me see the light. How can I track an event goal that doesn't happen on my website?
Alternatively, I could create a new calendar with the same settings as the original one and test them on different pages. This will really be my very last resource because there's a lot involved in these calendars, such as automated email, Zapier integrations, etc, etc.
If anyone can help me figure this out, I'd appreciate it!