So if you want to say you walk quickly you say 早く歩く. Great.
Now, suppose you want to say you walk unquickly. Could you potentially say something like 早くなく歩く?
The obvious answer is you simply say you walk slowly, but someone I tutor asked me what the negative form of an adverb is and I was caught of guard. I've looked around and didn't find anything so I assume it's just not a concept in Japanese but I wanted to make sure I gave them the correct information.