Mixbus 11.1 comes with the Harrison Creator Pack. Check this page for more information
https://harrisonaudio.com/creator-pack
Once Mixbus 11.1 has been purchased and downloaded you will see a new option in your user account to access that content.
Log in to your account and click on My Products/Software Products then scroll down till you see your Mixbus 11 serial column. You will see a link that sends you to a page to then claim your serial numbers and instructions to install the 3rd party products.
This is what you will see on the next page.