@smittyphi I assume you are referring to the disk version of Civ IV. I'm not sure if you just have the vanilla game, or with expansion, or the Complete Edition. Regardless, there are known issues with the old disks with the release of Windows 10. (The issue is not a bug with Civ IV, but rather a Windows Update at some point that disabled SecureRom due to security risks)
I have not used the disk version in many years, so I have no direct experience with this issue. I used a non-steam DD version for many years, and now use the Steam version - basically another DD version. DD versions don't have this issue.
If you have and play only BTS, which is the ultimate version of Civ IV, there appears to be a workaround to this problem - for BTS only. This is oft discussed over in the tech form here:
https://forums.civfanatics.com/forums/civ4-technical-support.159/
And this thread appears to be the one mentioned in the thread you linked above, that has much discussion on the topic:
https://forums.civfanatics.com/thre...dministrator-privileges-and-try-again.552140/
The reason one may get BTS only to work is that BTS was patched some years ago not to require SecureROM or a disk to run.
My recommendation though, if you are willing to spend a few bucks, is to find a DD version of Civ IV Complete on sale at Steam or another good vendor like GOG.com. In fact, GOG is having a sale right now and the Complete version is 7 bucks...see here:
https://www.gog.com/game/sid_meiers_civilization_iv_the_complete_edition
If you are not familiar with GOG, they are a very respectable vendor and all their games are DRM free..it is their mantra.