First, new to the forum, and also new to ubuntu so hi I guess. Anyway, I just got my adapter in the mail today and attempted to use it with dolphin. Looking at this tutorial:https://dolphin-emu.org/docs/guides/how-use-official-gc-controller-adapter-wii-u/, I'm supposed to create a udev rule to allow access to said adapter, the problem is that I have no idea how to create a udev rule. I tried saving a file into /etc/udev/rules.d/ but it spits an error saying I don't have permission or something like that. I looked up some other solutions, but most of the other ones I saw gave conflicting answers, so, yeah. I'm still terrible at using ubuntu so the solution could be staring me in the face and I don't know it. 
Hopefully I come across an answer here.
Hopefully I come across an answer here.