I’m not exactly sure, I’ve not worked with digital ocean myself, can you google that specific error? and did you plug in the “example.com” bit? or was that directly in the error message?

One thing you could double check is by looking at your config file on your docker host, making sure that it in fact has your API key.

Note this command is being run on my docker host, which has the “default” api key (since I’m not using it) — yours should be different.

cat digitalocean.ini
# Instructions: https://github.com/certbot/certbot/blob/master/certbot-dns-digitalocean/certbot_dns_digitalocean/__init__.py#L21
# Replace with your value
dns_digitalocean_token = 0000111122223333444455556666777788889999aaaabbbbccccddddeeeeffff