Upgrade from starter to essential

I just purchased essential and the download didn't come as a zip file. When I convert the folder to a zip and try to upload I get an error

Hi dipset3576,

You can't have something else than a zip file.
Maybe you are doing something wrong, be sure that you save the file, and don't open it to zip it after.

If the problem persist you can install HikaShop via FTP, you can find documentation here:
www.hikashop.com/en/support/documentation/faq.html#installation