Hi Steve,
I get the frustration, but here's what's actually happening.
Your Mac is on macOS 12 (Monterey), and current versions of Word simply don't support it anymore. Microsoft only supports Office on the 3 most recent macOS versions, which right now are Tahoe, Sequoia and Sonoma. So anything below macOS 14 can't install or update Word. Monterey got dropped from that list back in 2024, which is why the installer keeps failing no matter how many times you retry. It's not something you're doing wrong.
So realistically you have 3 options.
First, check if your Mac can upgrade. Go to Apple menu > System Preferences > Software Update and see if macOS 14 (Sonoma) or newer is offered. If yes, upgrade and then Word will install normally. If your Mac is an older model that's stuck on Monterey (a lot of 2015 to 2017 Macs are), then desktop Word just isn't possible on that machine.
Second, use Word in the browser instead. Go to microsoft365.com and sign in. Word, Excel and PowerPoint all work there for free, even on Monterey. Microsoft themselves point people with older Macs to this.
And for the refund, honestly nobody here on Q&A can process one, it depends on where you bought it. If you bought directly from Microsoft, sign in at account.microsoft.com/services and cancel the subscription there, or use Order history > Request a refund if it was a one time purchase. You're usually eligible within 30 days of purchase or renewal. If the option doesn't show up, contact support at support.microsoft.com/contactus and they'll handle it. If you subscribed through Apple's App Store, the refund goes through Apple, not Microsoft, at reportaproblem.apple.com. And if you bought it from a retailer, the return goes through them.
More on the macOS support policy here: https://support.microsoft.com/en-us/office/lifecycle/officeinstall/upgrade-macos-to-continue-receiving-microsoft-365-and-office-for-mac-updates