Oh, we (our congregation) is a new MAPS subscriber, we downloaded this from their site. All the apps are executables (.exe) (or executables in zip files). But not the OS. We checked with MS before signing up. ... We are a small congregation that hires out developers from time to time, then shares what is created with other small congregations, like that. So we don't list ourselves in any of their marketing stuff or the like, more just tiny, private developer. But I am not a developer, and I am responsible for updating these 2 machines, and ... sigh. Volunteering can be fun, great way to learn new things.
Well your .img file is intended to be burned to a DVD/CD by any of many free and purchased software out there. I am aware of one such program called MagicISO which cost around $30.00 from their website. There is a trieal version but not sure what the limitations are. I am sure there are many others out there you can look for. Probably a few freeware apps that will do what you need.