For Kodi 16 and above, you need to use the complete portal address, which is
Code:
http://s1.iptv66.tv/c/index.html
Also, the MAC address you would use is something you make up, starting with 00:1A:78, and the last 6 characters can be anything hexadecimal... maybe the real last six of the actual box. The actual hardware MAC is not relevant when using Kodi.
In general, I don't recommend anyone using "Stalker" based clients, and to use "donation number only" methods, using M3u lists, or a add-on like xtream-codes IPTV or Potato TV. MACs are used if you have a box where you have an IPTV app where the MAC is set in firmware, or if you really need to use PVR Staker, or the STB Emulator.