Does anybody know what exactly i must do to get it working?
You need to self-build an LE image with their drivers or whatever hacks are required to make their cards work patched into the Linux kernel. We used to have driver add-ons that overlaid some of the so-called "popular" card vendor drivers; but those were a complete pain to maintain and over time nobody on staff wanted to continue/make the effort and they were dropped. We encourage users who want DVB cards that "just work" under LibreELEC or any other mainstream distro to vote with their wallets and purchase products from vendors who upstream their drivers/firmware and engage in mainline kernel support for their products. TBS make some nice hardware but do not fit that description. Caveat Emptor 
