You need to install Oracle Access Manager (OAM) before configuring Oracle Traffic Director. Also, there are version and environment related limitations for installing OAM.
Before you can configure Oracle Traffic Director 12c WebGate, you must install one of the following versions of Oracle Access Manager.
It is highly recommended that Oracle Access Manager is installed in its own environment and not on the same machine as WebLogic Server. Oracle Access Manager and WebLogic Server can be installed on the same machine if they are both 11g versions.