The page I linked to above contains a link to a zip file (dexed-0.9.3-win.zip). This zip file contains 2 dll files within its folder structure. Both files are named the same (Dexed.dll), but you can tell which is which by the name of the folder they are in within the zip archive.
After placing the DLL file in your DLL folder, did you do a VST reset and then a scan from Preferences | File | VST settings.