I'm on the ICO site trying to withdrawal but no withdrawal button.
There are instructions in the second comment of this thread. Basically you will have to go to the 'PAYOUT' tab. Please make sure you have the correct 12 word seed saved.
Payouts (withdrawals) are processed manually, next one in ~two weeks and after that they will be done monthly.
I am on the payout page and it says my KMD balance is zero
You must have already requested a payout/withdrawal. When it is pending your balance goes to zero. So now you will have to wait for the payout to happen in 2 weeks.
You can check your investment & withdrawal history and status from the home page.
Does holding my supernet asset in Iguana pay out shares or something of that matter?
I'm getting a little confused xD
Yes, it pays you something.

As long though, you have your wallet open and running...
This works for me btw!

When I try to withdraw from Poloniex to the Agama wallet, it says wrong address but im definitely getting the right one.
What should I do?
SuperNET is a NXT asset, so you will have to send it to some NXT wallet. You could use SuperNET Lite wallet:
https://supernet.org/en/products/nxt-servicesWe will import our assets to Agama later