Thanks for the reply! I managed to make it work with a wildcard record. My (only) app is on the www [dot] subdomain and the wildcard redirects everything to www [dot] so it works in our case. Strangely enough, my [dot] domain [dot] com also works now. No idea how or why.
Should I still implement your suggested solution? Also, could I execute the command in the DigitalOcean browser console using my admin-level access (not root)?