Use my own landing pages?

Wondering if this is possible.

I want to use my own landing and sales pages and then use a popup to allow people access to the webinar – reply or whatever. I see this done on webinarjam here for example: https://ebenpagantraining.com/build-my-wealth/

If you click the button, you will see a lightbox popup which is handled by webinarjam.

Also, would be nice to have a shortcode I can use on my own sales pages so that I can indicate when the next few webinars will be running (for reply for example)