If you find yourself getting rsync error 13 when using it on cygwin, check the permissions on your source folder. For some reason, out of the box all directories have 400 permissions, and if your destination folder needs anything higher than that, rsync will fail. Make sure you execute chmod -R 755 on the source directory - assuming it’s in your cygwin box-.

Also, if chmod fails, make sure you ran cygwin as administrator on your Windows machine.

Worked like a charm for me!