By default you have to use the default.yml for your first group in luckperms, its possible to re-name this in the luckperms config:

group-name-rewrite:
  default: Deckhand

The issue is, autorank does not read this name rewrite properly, a new player that gets put into "default" group can then not rank up to the next group as its prerequisites is not recognised, if I change it to the name in set in group-name-rewrite Autorank throws a hissy fit telling me there's an error ever second.

I have had to set my default group to "default" to get it to work, as it does not respect renaming it in luckperms.

default:
  prerequisites:
    in group:
      value: default

Unfortunately, that's a bug with Vault.

Autorank does not directly access LuckPerms, but uses Vault as a middleman. Vault apparently does not support this rewrite function.