This is not a skill challenge. This is an adventure written up in the pattern of a skill challenge. It uses very little of the skill challenge rules.
The skill challenge rules when put into their most basic form are:
PCs make skill checks of any kind(which PC makes them and which ones they make aren't dictated by the skill challenge rules). Each one that is higher than X succeeds and each one lower fails. If you get X successes before Y failures, you win the skill challenge and get the XP. If you fail, you still reach your goal with some sort of disadvantage and no XP(though, apparently they errata'd it to allow XP even if you fail later, I haven't seen those new rules. LFR has it's own house rule to give out half XP on a failed skill challenge).
However, that gets rather boring. So you put those skill checks within context of a storyline so it sounds like you are actually doing something and not just rolling dice.
This is a perfectly valid skill challenge:
Figure out the symbols on the wall
8 successes before 3 failures
Player: "I make a Arcana check to identify them. 22."
DM: "That makes it, the DC is actually 12. You start to understand the symbols."
Player: "Oh, I actually make 12 on a 1."
DM: "Ok, then you make 8 successes without failing and understand the symbols."
The problem is that often the act of putting those skill checks in context falls entirely on the DM. The first couple of skill challenges that authors started to write....even before the 4e rules had come out looked a lot like the above.
WOTC kept giving us weird and conflicting advice on how to write skill challenges(it didn't help that the last beta of the 4e rules had completely different skill challenge rules from the final version). We had a panel from a couple of the R&D people who tried to explain to us exactly how to write an interesting skill challenge. The problem appeared to be that none of them had the same ideas on what exactly a skill challenge was.
Some of the advice we were given was: "Each skill check should be accompanied by a description from the DM to help make sure each PC had to make a roll and the skills needed were a variety."
The very first skill challenge I ever saw was the one written by Chris Tulach for D&D Experience, a couple of months before 4e came out. I ran that adventure.
He had a skill challenge where you were trying to run away from people looking for you. Each skill you succeeded on would put you into a new situation you had to deal with. For instance:
"You need to hide, but all you see is a wall that's rather tall, a trash can, and a crowd. You can use Stealth to hide in the trash can, Athletics to climb the wall or Diplomacy to blend with the crowd." You'd ask each player what they were doing. If they all succeeded, they'd still need more successes to complete the skill challenge. So you'd say "Alright, the majority of the guards looking for you pass. However, one spots you and you are forced to run down an alley to get away from him. You can make an Acrobatics check to leap up and grab a railing above you, Athletics to climb the building, or Stealth will let you hide in the alley and wait for them to pass." And so on until they succeeded or failed.
However, later we were told that wasn't a good example of a skill challenge because the players should be choosing which skills they use, not the DM. The idea was to encourage creativity in how their skills could apply to the situation. You should ask the players what skills they use and how they are using them. But this caused players to always choose whatever skill they were best at and often degraded into senseless rolling.
Later we were told to merge the two methods by sometimes allowing players to decide which skills they used but sometimes having mandatory skills that the entire group needed to make.
Overall, the rules for Skill Challenges and exactly what the people at WOTC thought they were kept changing and were kind of a hot mess.