Your logs indicate that the downloaded file is corrupt: Error: The cabinet file 'Main.cab' required for this installation is corrupt and cannot be used. This could indicate a network error, an error reading from the CD-ROM, or a problem with this package.
First, please rename the installer .exe file you downloaded and save it in case Serif wants to look at it. @Lee D or one of the other staff can provide information on where to upload it if they're interested.
Next, try downloading again and compare the file sizes of the original and new downloads. Then see if the new one works better. If not, you might try downloading with a different browser.
