Hello Charles,
The v2.21 download contains the full set of software, so you don't need to install any earlier versions first. You just need to:
1. If you have any important settings, combination files etc, make a backup of the following folder:
[Hauptwerk installation folder]\HauptwerkUserData
2. Uninstall Hauptwerk, ticking the option to remove all files.
3. Run the downloaded v2.21 installer and select the Custom option to install to your new location.
4. Restore your backed up copy of the HauptwerkUserData folder to its new location, replacing any files there.
5. Launch Hauptwerk. Check that your previous settings are still in effect.
6. Reinstall all sample sets.
Hauptwerk versions 1.00-1.24 can coexist separately from v2, so you can keep v1 installed where it is presently, assuming you have one of those versions.
Best regards and a happy New Year,
Martin.