Apologies - itch doesn’t always notify me of comments like this so I missed this for awhile. Bale creation with a new fillType is an additional installation process I did not cover. That’s why, for simplicity you can set this up to drop Grass_windrow instead of alfalfa windrow.
In your map you’d need to start with the BaleTypes xml and follow the trail to any i3ds and XMLs of specific bale types and sizes to introduce alfalfa_windrow or dryalfalfa_windrow as well as defining bale textures, etc.
if you can find the baleTypes.xml, use that and follow the paths down stream. It should start to make sense. Also - log errors are likely happening when you try to bale without proper setup, log errors also help you fix!