Go to your Social Settings
From your HubSpot Dashboard, navigate to Social > Social Settings.
Click the Connect Bitly account button in the Custom Short Links section
Scroll down on the page to the Custom Short Links section and click the Connect Bitly account button.
Authorize on Bitly
Click OK to allow HubSpot to access bitly and authorize your account.
Sign in with your Bit.ly account.
Click the Allow button to let HubSpot connect with your Bitly account.
Verify that you've connected your account
You'll be redirected back to the Social Settings page once you complete authorization on Bit.ly's site. You will then see the Bit.ly account you've connected listed on the page and the custom short domain that will be used for shortened links. Additionally, all of the links shortened by the social media tools will also be stored in your Bit.ly account so that you can access them from there as well.