If you want to make a ISO then you dont need anything from proxmox. Go to a windows board and ask for support howto create a custom windows installation media I'm sure you get much deeper and more detailed feedback then we can ever give. Cause making windows installation media is absolutly nothing related with a virtualisation technology and it is very off topic here.
If you want to duplicate your template from your primary to your secondary proxmox node as described in the first post i can't see what you want to do with an ISO file.
If you want to duplicate your template from your primary to your secondary proxmox node as described in the first post i can't see what you want to do with an ISO file.