Can you please go to C:\Program Files (x86)\Real\RealPlayer and look for a file name videodl.exe. Can you please right click on it and go to Properties. I would like you to click the Details tab and let me know what the Product Version is?
Please note: It should be 2019.06.21. If it is not, the instructions were not followed correctly. Please try that once again.
You may also have a firewall program that may be blocking RealDownloader from detecting videos. Can you please let us know what error you are receiving and which web browser you use to download videos?