Hi,
I test the link (on different browsers, with and without an account) and it is working good. Strange that you can't see it.
You can find the "Essential to Business" page under the "Extensions" menu :
www.hikashop.com/extensions/upgrade-my-version.html
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.