Their website says you can download the Core and Maps v1.01 off of Steam Workshop and it is the same as Complete. I was having the same issues with a different download once and successfully downloaded it off of Steam Workshop.
If you do get it off of the Workshop, you also need to navigate to the location of the download, cut it, and paste it into an @Folder in your Arma directory like a normal mod then unsubscribe. That way it won't auto update.