Sync Clash from ipod 4 ios 6.1.6 onto iphone ios 8.1.2

What i did was I got the same game center. I went to clash, I went through the tutorial. Then I went to settings on Clash and with my ipod 4 hit old device then pushed transfer to iphone. It says that im not logged into the same gamecenter which I am. Then on my new device, when I push this is the new device it says enter link code. I don't know where that is. And my town hall is only lvl 2 so I should be able to do it. What can I do to make sure my better place gets on my iphone.