Gregory's ServerThis was surprisingly tricky to set up on a modern computer:
• Windows needs to be 32-bit because the Eudora conduit is packaged inside a 16-bit installer. Windows 10 needs some extra support files to run 16-bit apps, so I installed Windows 7 in a VM.
• Internet Explorer doesn't work anymore, so had to copy the Firefox installer into my VM's hard drive in order to download Palm Desktop, drivers, updates, etc.
• Outlook needs to be new enough to run CalDAV Synchronizer: https://caldavsynchronizer.org to import my NextCloud contacts / calendar
• Outlook also needs to be old enough to sync with HotSync and the Eudora conduit. Office 2007 is the minimum version that meets both requirements.
• HotSync and Outlook both need to be running in Windows XP compatibility mode in order for them to talk to each other and transfer data
• HotSync.exe needs to run as administrator, as it tries to write all the backups/sync data into Program Files instead of the user directory.
• Outlook.exe also has to run as administrator, otherwise HotSync wont communicate with it while running as administrator
• My USB-serial adapter needs drivers on older versions of Windows. They were nice enough to include them on a CD, but none of my computers have an optical drive anymore. Downloaded them from the manufacturer's website with Firefox.
• CalDAV Synchronizer requires a recent version of .NET to run, so I had to get Windows Update working with Legacy Update by @kirb: https://legacyupdate.net/
The HotSync conduit update for Outlook 2007 is very difficult to find, luckily there's an archived copy here: https://www.palmdr.com/important-links. There are unofficial patches for 2010 and 2013 here: http://pizzaboy192.com/download/ but I'm using 2007 with the official update from Palm.