How do I set user content to display based on a related job?

Hello! About a week or two into using Bubble and have hit a barrier I can’t surmout.

I’m creating an app that displays a “job card” for each task (these cards can be publicly visible to anyone.)

Within this is a sub Group that contains user-data notes (these notes should only be visible to the user.)

To solve this, I’ve created a job data type, with name, text details etc.
And I’ve created a data type called user-data. In this type, the primary field is the related job, but it also contains a to do/done etc status field, a text note etc.

What I want to achieve is:

When the job card is defined, if there’s a user-data entry with a matching related job field, set it as the data source for my user data subgroup.

I just can’t make it work – can anyone help?