So I downloaded the Synplant Trial and it took me through an authentication link. When I got to the link, the site said I had made now dowloads or purchases. I do not know why. I've tried to open them in Logic Pro X 10 but it is not working because I cannot find them. Any help?

Hi, sorry to hear about your troubles. You don't need to authenticate to run the trial. Synplant should always show up in your host after installation. Did you check out Logic Pro X main menu -> Preferences -> Plug-in Manager? If you find it disabled or with an error, make sure you enable it and reset & rescan.