Add each of the following columns:
Add a Status column
Use labels like Not Started, Working On It, Stuck, Done — match your Portfolio board's expected labels if it has specific ones
Add a People column — name it Owner
Add a Timeline column — name it Project Dates
Add a Numbers or Priority column if your team tracks it
Match your Status labels to the Portfolio board
If the Portfolio board's Mirror column expects specific Status labels (e.g. exactly "Working On It" and "Done"), your board's Status column needs to use those same labels, or the rollup won't display correctly.