You still can participate in the Freeletics Pullup Day. This isn’t about doing the skill path - it’s about doing pullup variations (on your own choice, no coach needed!) that specific day.
Edit: the skill path is just a suggestion as preparation. You can also use the free e-book Mastering the Pullup mentioned in the official blog post. That’s a good e-book with which I learned the Strict Pullups.
The skill pathes are a new in app feature and the Freeletics Pullup Day is here used to promote the Pullup Skill Path. Don’t worry if you are not on that Skill Path by now. Pullups are a long-term skill and it’s totally ok to do Assisted ,Shoulder, Negative or Jumping Pullups that day (in fact it was the last years).