You don't have to. But it would be easier to go through some of these tasks, if you were to complete these milestones in order.

For example, the fourth stage Contributor requires you to create issues, i.e report bugs, types, etc. If you had already completed the first stage Explorer (coming soon), you might already know what issues you'd like to report. To complete the third milestone Advocate, you need to have in depth knowledge about the erxes platform. So, we highly recommend you go through these stages in order presented to you.