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 also need a token, to prove you have passed the Test of the Orc Marauder.
However, it seems that your level is not high enough, and you have not yet passed the Test of the Raider. First, work to raise your level to 20 or higher. To take the Test of the Raider, 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. Use a Gatekeeper to go to the Orc village.