The .HideCommandPromptWindow property was available from version 1.0.18

You are getting that error because you are using an old version of the wrapper. My guess is that you are using version 1.0.17.

Please download the latest version from the below link and try again. I tried with version 1.0.17 and I got the error but when I installed the version 1.0.18, it worked just fine as shown in the screenshot below.

Selenium Wrapper Setup File

Hope it helps

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