Hi André-Philippe, thanks for reaching out!
If you're on an Explorer Plan, you can integrate with HubSpot’s REST API by utilizing their API documentation along with Clay’s HTTP API and Webhook table features. These tools enable you to replicate the functionality of our native integration by manually configuring calls to HubSpot’s endpoints.
You can still import/export contacts into a list with the Explorer plan, but it will just be more complicated than using our built in Hubspot integrations on Pro especially if you have a lot of properties.