High Prefect Osborn:
To become an Raider, the appropriate level and token are required. Your level must be at least 20 to qualify to change profession. You need a token to prove you have passed the Test of the Raider, as well.
I am satisfied with your level, but it seems that you have not passed the Test of the Raider. To take the test, go to Prefect Karukia of the Orc village. He will tell you everything you need to know. If you pass the test and come back, I will change your profession.
To get to the Orc village, use a Gatekeeper.