At the beginning Zed jung can only be used to help push out/pressure lanes and harass unless you team has a lot of cc to set him up with a gank pre six. But once you hit level six as soon as you gank as long as your opponent is not feed you will defiantly get a kill (saying that don't go tower diving a le blanc because you will just fallow her all over the place).
Zed jungle is also useful if the rest of your team is ap as late game you will be an equivalent of a mid or top zed so you will provide the same damage and even if you cannot provide the super insec lee sin kick easily helping win a team fight is just as good.

Now these runes make it so much easier to farm the jungle as the life steal just stop you from taking as much damage therefore if you want you can take a ward instead of two of you starting pots. Also the extra attack damage given will give you that extra damage to clear the buffs quicker and you will generally be more efficient.

With items you start almost like a vi just with elder lizard you don't do a great amount of damage till you it level 6 but when you get your brutalizer you become much stronger and this makes it easier to get kills. late game once you have 6 items you can swap out your lizard for a G.A or a Q.S.S which could be more useful. Also you could even swap your bots and then just rely on the speed up from youmuu's just get you around the map. only get the hexdrinker when you are against ap because a randuins would be much more useful against a full ad team.

On the way I have levelled up my abilities is your Q is the best for poke and clearing the jungle same for your E but your Q scales better that is why you level it up first. On the other hand you could level up your E instead for better jungle clear but yo would not have the same burst potential till later on into the game.

Zed is just a fun champ to play in the jungle who can gank easily with his clone and can be played top jung or mid. Thank you for reading!

P.S SKT Zed is the best!!!