I tried that link, but didn't know what to do with the files. Read my subsequent replies.
-It is a compressed 7-zip file
-unzip it with 7-zip (if you don't have it install it)
-unzipped there are 3 files
-the pdf are the instructions
-the instructions say
Installation
Copy 'SDRSharp.FrequencyScanner.dll' to your SDR# folder
Update the 'Plugins.xml' file with the following line (if it has not been done):
<add key="Frequency Scanner" value="SDRSharp.FrequencyScanner.FrequencyScannerPlugin,SDRSharp.FrequencyScanner" />
Done!