We're making an exception to our existing policy for those who wish to participate in this program.
Cool, much appreciated!
The input box doesn't come up for me, all I get is "The promo DIVEIN10 for $10.00 was applied to your account." which if I remember correctly, was when DO did codes over Twitter quite a while ago :p
Go to cloud.digitalocean.com/support and create a new ticket, giving them your promo code and asking nicely, and they'll put it through promptly in my experience
I don't know if GitHub added it afterwards, but when you click to get the promo code from DO, they say underneath
"Contact DigitalOcean support with your unique promo code if you have previously redeemed a promotional offer, credit card required for activation"
https://www.digitalocean.com/help/pricing-and-billing/