It may be easier to let it download late at night (or overnight), when there is less traffic. Download time will vary depending on the speed of your modem, Internet traffic and your Internet provider (ISP).
You can download the Inklingo collection onto a computer with a faster connection, copy it onto a thumb drive or CD, and then copy onto the desired computer. It does not matter which computer you use to download, but be sure to only activate on the computer you want to use for Inklingo.
Even if you copy the files onto your computer from a thumb drive or CD, you will need to go online to activate the first time. Activation only takes a second, so a slow connection is not a problem.