Hi there,
Check out this exercise on the Wix Content Manager Learning Center : https://learn.wix.com/en/article/getting-more-out-of-datasets#exercise-filtering-content
Start from Step 6 on the right hand side (or do the whole exercise if you want to). This will show you how to add a ’ Related Items ’ repeater using filters. Looks like you are trying to create something similar.
Hope this helps!
P.S. I know that the exercise is in the Wix editor but the process is the same for Editor X.