Solution: I created a custom field for contacts in AС (the initial service) and HubSpot. In
Make.com, I set up a webhook to receive data from ActiveCampaign. There are two scenarios: -for an existing contact in HubSpot, -for a new contact. We update the data and automatically insert a link to this contact in HubSpot into the custom field in ActiveCampaign. In HubSpot, we insert a link to the contact from ActiveCampaign.