This is actually a bug report. On https://cloud.digitalocean.com/droplets/new, after entering an ssh key, the next field says "Please choose a hostname for your droplet." and there is a light-grey textbox. The obvious thing for a user to do seems to be to click the textbox and enter the hostname suggestion. However, when they click the textbox, the cursor doesn't appear in it and they cannot type into it.
After some searching around, It seems that I can scroll to the top and enter a hostname there. Therefore, I'm not blocked, but this is a pretty jarring UX bug.