1. Navigate to Hubspot settings
From the top right corner of your Hubspot account, you'll find the Settings icon.
2. Navigate to Pages under Website
In the left-hand side navigation, go to Website -> Pages to open the page settings of your account.
Find the Site header HTML box on the Pages page and paste your installation script there. After, you can visit your own web page and check the status of your installation from Markettailor Script page.
The script is now included in all your created pages.
If you have multiple domains in Hubspot, make sure to only select the one that you want Markettailor to be installed on.