Thanks the previous response. I did have the HOF mod in the wrong folder, and moving it fixed the problem.
Now, when trying to load the save game for the GOTM, I get this message:
"The save folder you have selected is protected to ensure that the assets in your mod folder have not changed." Clicking OK closes Civ. The message implies that I changed something, but I don't think I have -- I'm new to mods & stuff. How do I find out what changed or what the problem is?
(When loading the save file, I get the "save file requires mod" message, it loads OK, and them gives me the message above. I tried loading the HOF mod separately, and playing a couple of turns in a new game, and that worked fine. It's only the GOTM save file that doesn't load.)