These instructions have worked for many of our customers. Something in your Windows is blocking the update.
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 us know what the Product Version is?
Please note: It should be 2019.06.21. If it is not, the instructions were not followed. Please try that once again.