Yes, that's how the UAC works when triggered from a non-admin account, and (most) installers cause the UAC to come up. If there's only one admin level account it defaults to that one, but I do have to enter the password. I treat it a bit like using "sudo" on a Linux/Unix machine--I don't like staying logged in as an admin account.
I get an Access Denied error on that link.
Since I already use AutoHotkey I used someone's example one-off AutoHotkey script to accomplish the Mute/Unmute, plus Play/Pause, Volume Up/Down, and Skip Forward/Back. I can provide the script and commands if anybody's interested. It can be used to simulate virtually any keyboard key, or even key sequences.
I think I've uncovered another bug. For some reason I'm seeing multiple entries in my command list on the website, even though my commands.json file doesn't have duplicates, and triggering one of the duplicated commands is problematic.