Your first ID pass

1. Properties ▸ View Layer ▸ Passes ▸ tick Material ID.
2. Open Material ID Export and set Output. //matid/ writes next to your blend file.
3. Press Render ID Pass. You get MaterialID.png.
4. Press Export Swatches. You get MaterialID.aco and MaterialID.csv.

Step 1 is the only one that is setup. The rest is export.