I have included the API key included at the end of the my URL string (i.e. hapikey='your_api_key') as suggested by you previously.
Is it supposed to be like this, https://app.hubspot.com/contacts/8571348/contacts/list/view/all?hapikey= 'a397fd41-678d-431f-aa91-1bd2648282cc' or https://api.hubapi.com/contacts/v1/lists/all/contacts/recent?hapikey='a397fd41-678d-431f-aa91-1bd2648282cc' ?
Please correct me if neither is correct.
But encountered this error when using REST connection,
I can see from the screenshots you've shared that you're getting a CSV response instead of JSON. The connection string appears to be incorrect from the URL which I see entered. It doesn't appear to include a valid HubSpot API call.
I am able to pull data from hubspot to qliksense for standard objects in HubSpot - Contact, Company, Deal, and Tickets, based on the endpoints suggested by you and in the guide.
But when I tried to pull data of dashboard (Reports -> Dashboards )from hubspot, by using this endpoint to call dashboard, https://api.hubapi.com/crm/v3/objects/Reports?hapikey=9aebb661-a618-4cb0-a9ba-ca14dea534a1.
But it doesn't seems to work and is it because this is considered to be a CRM Custom Objects API?
A custom object would be one created by you/your team within your own HubSpot environment. This would be unique to your enterprise account. There are instructions on how to create and define these in the section you've referred to.
Reports are not an object, which is why the endpoint you've listed is not working. Reports in the HubSpot UI are actually using the object data for calculation and presentation.