After connecting your Hubspot and creating the list, you may now proceed in importing leads.
Here are the following steps on how to import leads to your Campaign or List from the Hubspot.
On your Email Accounts tab, click Add Leads.
Select Hubspot.
Select a list from the dropdown menu and click Import.
Check the corresponding fields and click Upload all.
Note: Before we proceed in importing leads from Hubspot to your campaign or list, you need to connect your Hubspot to Instantly. After connecting, create a List in Hubspot from which you will import the leads. You can read this article about creating list in Hubspot.
Instantly will check for any blocked contacts and duplicates across all campaigns.