When you download, are you choosing Save or Run? If you are choosing Run, you may be getting a prompt from Windows immediately after the file is downloaded to the TEMP folder. I suggest saving the installer to your Downloads folder and then trying to launch it from there to see whether that works any better.

No dice. Still wants that dang password.

Could you post a screen shot of the dialog asking for a password? Trying to figure out if this is from Windows or something else. This article has tips on screen shots: How do I create a screenshot of my problem? Please blur or remove any sensitive information before attaching the image file to a reply.

After trying multiple ways to get you a screen shot and failing at that as well, I had a breakthrough with our Home Office. This is an office computer on a secured network and it was actually one of their encryption blocks. No wonder I couldn't figure out the password - it was a Home Office one! I do apologize for all the trouble - I am not very computer savvy so I never even thought of that as a possibility (nor did I realize my Home Office had Admin overrides on my field office computer). Thank you for all of your help!