Import Data to a Custom Object in NPSP

Hi ohana,

I am practicing importing data with NPSP Data Import Wizard, but I keep getting an error for Opportunity record not found on the trailhead. I went back to my NPSP Data Import's list view, Failed Data Imports, and the error I get back is that my trailhead storage limit is exceeded even though this is a new playground created just for this specific trail. How can I fix this to pass the trailhead?