Interactive Avatars and Knowledge base

I have been looking around to try and find some information about how the knowledge base actually work.
The demo shown here: https://labs.heygen.com/interactive-avatar?tab=public (click on the "+ Create New" button), just shows a field to enter a URLs. How about PDFs or documents or reports, etc.

Additionally, there is not enough information on the pricing page: https://www.heygen.com/api-pricing
For some reason we have the impression that only Enterprise account can create Interactive Avatars, yet it mentions 1min in some places and 2-3 in other places for the $99/mth account...then, it is $89 seat or $99/mth? https://www.heygen.com/pricing
We're really confused.

We are a small shop, and looking to create 3 interactive avatars for specific topics, but not sure what to choose, how long the user can actually interact with them for, and we're not sure what to do next.
We tried your chatbot Support, but that just took us in circles, and the Forum, well, that is how we ended up here in the Discussion section.

Can anyone help!?

Thanks.