Customers in Fusebill are linked to Contacts in HubSpot. It's not necessary to link to an existing Fusebill customer, as long as you're willing to have the customers created from within HubSpot.
In Fusebill, there will be an additional contact link available which allows you to directly link existing Fusebill customers to HubSpot Contacts:
This is the interface in the Manage link which allows you to directly link to an existing contact in Hubspot:
The HubSpot ID is in reference to the contact ID:
This ID can be found in the URL of the contact in Hubspot.
For example: https://app.hubspot.com/contacts/6246015/contact/101/
The ID is 101
In HubSpot, on a HubSpot contact, in the list on the right, the Fusebill customer will appear at the bottom:
You may want to move it up in order to raise visibility. If the HubSpot Contact is not linked to a Fusebill customer, it will display the following:
It's not necessary to have the customer linked to Fusebill yet, as the workflow is ideally to set the customer up in HubSpot first, then push it to Fusebill as part of the deal workflow which includes the customer and subscription information.
The primary workflow and biggest changes are what starts from the deals.
Fusebill Adds an object to the deal, so once a deal is created you can scroll down or potentially move the Fusebill subscription box.
From here you can add the Add Subscription button to add subscriptions to the deal.
Fusebill also populates some activity in the customer's feed, but this needs to be enabled first.
Navigate to a Contact in HubSpot, click "Filter Activity" and put a check beside Fusebill:
Any resulting activity after a HubSpot contact has been linked to a Fusebill customer will appear in this feed: