I'm attempting to edit a client's website created in Website X5 v9.  My main goal is to make it mobile responsive.  I'm unable to import the .IWZIP file my client sent to me.  On the attached screenshot the first (top) screen shows the message I receive when I first import the file.  The second screen (bottom) shows the message I receive when I click the Next button.  The second message is confusing because it says the file was created in a later version.

Is it possible to convert the file?  It should be noted that both me and my client are using the free versions of the software.

This is the client's website in case that helps:

http://www.newhorizonchiro.com/