The first type: to be a master and apprentice.
If the level is below 60 and there is no master at present, you can become a master's apprentice through a normal apprentice. When the level reaches 60 or above, you can complete the apprenticeship task.
The second type: nominal apprenticeship.
If the level is above 60 and there is no master at present, you can spend a prop "nominal apprentice card" to learn from the master in name, and immediately become the next generation of disciples of the master after the apprentice is successful.