I was finally able to get a workable download from Rufus, 3.4. I guess it's on the flash drive now. Assuming it is, how the heck do I boot into Ubuntu
Just to check, do you mean Rufus is on the USB or the Ubuntu boot image is on the USB?
Did you run Rufus and have it copy the Ubuntu files to the USB? If you did then you boot from the USB drive and have it install Ubuntu on a separate partition on your hard drive.
Boot from USB:
https://www.eightforums.com/threads/usb-drive-boot-from-within-windows-8.53296/
https://lifehacker.com/5991848/how-to-boot-from-a-cd-or-usb-drive-on-any-pc
Dual boot Windows and Ubuntu:
https://help.ubuntu.com/community/Windows