Well, that went really well!
After the first couple times trying it, I finally just set my system to run as administrator instead of just choosing run as administrator each time. I jhad never seen the browse button--just went through each version and tried the D & D, and then spent hours trying to figure out if D&D could be restored to windows 10, which seems an exercise in futility. Just now when I went through it again, YES, the browse button was there, and the card was okay and it all installed easily!
Thanks for all your help and your patience!! Do you have any idea if a pdf exists with the directions for CHDK? I have several articles with them, but wondered if it was posted somewhere as a standalone that I could load on my iPad and take with me on my trip. I look forward to getting some new use out of my old camera in Costa Rica!