I'm assuming that they recommend a droplet with 1GB of memory which comes with 30GB of storage. MySQL takes up a good chunk of resources on the 512MB droplet.

That said, I host three wordpress websites off a 512MB droplet with 20GB storage. Just fire up a barebones 512MB droplet and install wordpress yourself. Be prepared to play with a lot of settings and configurations to not run out of memory all the time.