Hi,
For your first issue ; Please re-download the latest package from there:
www.hikashop.com/my-account/your-subscriptions.html
and install it over the current install. It seems that there was a mistake already solved which was causing this error.
About the popup issue, it might be related to Joomla 3.4.4
Please apply the official Joomla modification : github.com/joomla/joomla-cms/pull/7845/files
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.