vSphere DRS should be enabled on an ESXi host cluster manually and this can only be done from vCenter Server.
Make sure VMotion is enabled and working on all the ESXi hosts in the cluster. Also, you will need access to the vCenter Server.
The following procedure explains how to enable DRS on a cluster:
From the vCenter's inventory home, navigate to the Hosts and Clusters view.
Select the cluster, navigate to Manage | Settings | vSphere DRS, and click on Edit.
In the Edit Cluster Settings window, select the Turn ON vSphere DRS checkbox. Leave DRS Automation, Power Management, and Advanced Options at their default settings for now and click on OK to enable DRS.
The cluster's settings page should now show DRS as enabled. It should read vSphere DRS is Turned ON.