Help with form pre-populating contact form when user fills form in a separate domain


We purchased a tool called ion which allows us to create quizzes and assessments. We have integrated this tool with HubSpot so that when a user completes the form on ion, the contact information gets passed through to Hubspot. That is working properly.

The tool uses a subdomain. I have added the tracking code on ion and set HubSpot to track that subdomain.

The issue I am running into is that after someone completes one of our quizzes or assessments, we have a call to action for them to contact us for more information which links to our contact us form that resides on our corporate website. The form should pre-populate with the user’s information so they don’t have to put their general contact information in again, but the form is not pre-populating with the contact information if someone fills out their info on one of our ion quizzes or assessments.

The contact us form is set to pre-populate and it works if someone has filled a form out within our corporate website or HubSpot landing pages.

Is there anything else that I need to add to our ion pages so that HubSpot recognizes the user when they go from the ion page to the corporate website page?

Here is the example:

In theory, the contact us form should have the users first name, last name, company, etc. fields prepopulated because they already gave us this information in the quiz.

Anyone have any insight or advice?