In order to play on these servers, you have to install ZDaemon client first, so visit client's official site to download it:
Of course, you must own legal IWAD files, you can buy it here:
01 - ZDCTFMP1+2+3 (5 on 5 best maps)
02 - ZDECTFMP2 (5 on 5)
03 - ZDMEGACTF
01 - Gothic99
02 - Cybercrime3
03 - The Last Strike DM II
04 - Nutty
05 - Crucified Dreams
06 - Greenwar
07 - EDL CZECH
08 - MAP01
09 - MAP32 Botmania
10 - Greenwar II
11 - Zodiac
12 - Czequisite Corpse
01 - Ultimate DooM
02 - DooM II - Hell on Earth
03 - TNT: Evilution
04 - The Plutonia Experiment
05 - Operation: Drown In Blood (BADCORE MASSACRE)
06 - Operation: Drown In Blood (standard)
07 - Drown in Blood: Dietest 1.8 (BADCORE MASSACRE)
08 - Drown in Blood: Dietest 1.8 (standard)
09 - Invasion UAC4 (BADCORE MASSACRE)
10 - Invasion UAC4 (standard)
11 - Rocket Jump Space 9f
12 - MasterJumps 9y
13 - Heretic: Shadow of the Serpent Riders
14 - 2002 A DooM Odyssey
15 - Icarus: Alien Vanguard
16 - Plutonia 2
17 - Eternal DooM III
18 - Lost Episodes Of Doom
19 - Knee Deep in Phobos
20 - Invasion UAC5
21 - NIGHTMARE Ultimate DooM
22 - NIGHTMARE DooM II - Hell on Earth
23 - NIGHTMARE TNT: Evilution
24 - NIGHTMARE The Plutonia Experiment
25 - The Alien Vendetta
26 - Whispers of Satan
27 - Phobos Massacre
28 - Vile Flesh
29 - Master Levels for Doom II
30 - Doom the Way id Did
31 - Doom the Way id Did - The Lost Episodes
32 - PhobosDeimos Anomaly
33 - The Ultimate DOOM: No End In Sight
34 - Doom 2 the Way id Did
35 - Czequisite Corpse