Not sure where you heard their customer service is "shoddy at best". All my interactions with them have been very good.
I know they are currently working to get the second batch of Evos out so they may be running a bit behind in replying to emails.
I thought there was a button or something similar that said "Get Code" on that screen and a code was sent to my email, but it has been over a year so I may not be remembering correctly.
I just got my Chessnut Air in yesterday and I downloaded the app. When trying to create an account it has a text box at the bottom for "confirmation code":

After entering email, user name, password it will not let me continue and I've even tried pasting something random in there in the event it was a security number or something to that effect that is set by the user as another means of verification. Anyone seen this? Probably a shot in the dark but thought I would ask. I've already contacted Chessnut as well although I hear the customer service is shoddy at best.