I haven’t personally used Hubsppot, so this is just general advice… but this should be dead easy…
There might be some HubSPot plugins available that do it all for you, so I’d start by looking for one…
But failing that, it should just be a case of setting up an API call from your Bubble app, to create a new contract in Hubspot, and pass the relevant contact data in the call.
If you’re familiar with API calls and using the API connector then it should only take a few minutes to set up (you’ll need to refer to HubSpot’s API docs to see how to do it)…
Otherwise, and assuming no plugins are available, spend some time learning the basics of APIs and how to use the with Bubble, then just set up the relevant call in the API connector and you’re good to go.