The Dunning-Kruger effect is grossly overestimating one's own skill. I think that's the opposite of what you meant.
They probably meant Impostor syndrome[0] instead.
I have thought about and battled with impostor syndrome a LOT! So much so that I wrote this incredibly long article about it. I hope it's useful.
http://www.geekmindfitness.com/mindfulness/how-mindfulness-m...
"This place is overwhelmingly full of smart people, and I sometimes feel out of place!"
Don't feel out of place. You may just be suffering from Dunning-Kruger effect.
https://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
The smartest people for me are those who can drop all pretensions and learn as much as they can. You're well on your way.