Hi CaptJDK - I packaged the latest BaseSyncMFD, so can tell you for sure how to install it. Download the .zip file from
www.OrbitHangar.com into a download directory (e.g. C:\OrbDL) and keep it handy for the next time you are doing a clean install. Right-mouse on the .zip file, and select Extract All. Select c:\Orbiter (or wherever your Orbiter install is) for the destination and hit Extract, and the files will unpack over the top of the Orbiter installation, preserving the directory structure in the .zip file. In the case of BaseSync, you can check that there is now a file c:\Orbiter\Modules\plugin\BaseSyncMFD.dll (or wherever your install is).
BaseSyncMFD v2.6 now requires you to install ModuleMessagingExt v1.1, plus Visual C++ 2010 runtimes. If you miss either of these, then you will see errors starting Orbiter.
Note that in general, you can simply unpack .zip files like this. Always look in the .zip file though to see if the structure looks reasonable to overlay into the Orbiter structure. (E.g. does it have a set of directories that match the Orbiter structure). If you see a single .exe inside the .zip, then unpack the .zip in a temp directory and run the .exe (as the developer wants you to run a program rather than a simple unzip). You may also come across .rar riles, whish is just another type of .zip file. For these, use a free utility like 7-zip to unpack them.