I'm running into a problem installing Smith Cart trial version (3.80.00)

I was originally successful installing the module, however when I went to configure the settings of the Buy Now module, I selected the Enable VAT/GST Tax settings and the Tax Type list was not displayed (as shown in your manual on page 53). So I fgured I must have done something wrong.

So I decided to follow your instructions and unistall the Smith Cart module (and deleted files and database tables). I then proceeded to reinstall the module and after uploading the Smith.BuyNow03.08.00-DNN5.zip file, I received the following error:

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If you have reached this page it is because the installer needs to gather some more information, before proceeding.
The package contains files with invalid File Extensions (wsdl, ascx , ascx , ascx , ascx , ascx , ascx , ascx )
(Enclosed screenshot SmithCart_Error.png)

Do you know what would cause this error?
I noticed in other threads that the latest build is 3.85
Would that have anything to do with it?

Any insight would be greatly appreciated.

Many thanks in advance