1. Please, make sure that you've enabled "Use Folx to catch download links in browsers" option in Folx Preferences (
http://wiki.eltima.com/user-guides/downloader-macos/download-settings.html)
2. Please, make sure that Folx plug-ins are installed. See, if you have the following files on your disk:
~/Library/Internet Plug-Ins/FolxNetscapePlugIn.plugin
/Library/Internet Plug-Ins/FolxNetscapePlugIn.plugin
~/Library/ScriptingAdditions/FolxScriptAddition.osax
3. Check whether "Folx Downloader Netscape plug-in" is listed in Installed Plug-ins in Safari (Safari->Help->Installed Plug-ins).
4. If you use another browser (not Safari), please, let us know the exact name and version of the browser that you use.