You will have to get in touch with Steinberg about this. I know they will deal with the sale of the license behind the scenes, as the store front itself does not allow a direct purchase upgrade from HALion 1-3, to 5, so it must be done manually in the background. At that point, you will be given the appropriate download link which will have everything you need. Obviously, coming from any HALion version prior to 4, will mean you will need to download all content that comes with 4/5, so I am sure you will be given a corresponding link to obtain such an upgrade.