Go to your Zaps editor and click on Create a Zap:

Type Instantly in the search bar and select it from the drop-down menu.

In the event field, select New event.

Click Continue.

Click Sign in to connect your Instantly account and paste the API key.

Note: You can get your API Key from the Integrations page and copy the Zapier API key:

In the pop-up window paste your API key and click on Yes, Continue.

After you've connected your Instantly account with Zapier, click Continue.

In the setup action select your campaign and event type = Lead is marked as interested.

Test your trigger by marking a lead from the selected campaign as Interested and clicking on Test trigger.

Select Hubspot and select event = Create Contact. Click Continue.

Sign in to your Hubspot account to connect it with Zapier.

Click on Connect App.

Map the contact fields inside the Setup Action.

Run a test in Zapier and then check your Hubspot.

Note: The contact was added to Hubspot.

You can now publish your Zap.