The line between the rules and what goes is blurred, and also whether these rules are what was agreed. I don't believe the season will start without at least one rule being corrected. Probably best to email the rally department if you're thinking of running.
The rules say drivers don't have to compete in the team's championship, but a registered team has to enter the driver if the driver wants to score in the open championship. Driver's don't appear to have to be registered in the open Championship to score for the teams, but all drivers do have to pay €3000 registration fees (table, p102). Drivers don't have to be entered by a team to score in the WRC2 Masters Cup but these drivers do have to be registered in the WRC2 Open Championship in which they won't score unless they were entered by a team. The Masters Cup is an additional €3000 registration.
So registration for a driver who just wants to drive alone in the open championship is €3000 plus €10,000 for their own team to enter themselves in. A loophole-type flaw here has been discussed over several recent pages, which I believe is against the rules but was allowed last year.
Hopefully bandit12 will explain it clearer, or banish us to a new thread.