By default it is just placed on a BSP brush (unless it has changed recently), you need a higher resolution mesh in order to get a better looking ocean.
I just uploaded the mesh I use for my ocean sim (link in signature), it’s a 8192x8192 mesh with around 45k tri’s. To use with WaveWorks make sure to scale it up by 10x in the viewport, otherwise it will be a tiny dense ocean plane. Also make sure your material uses a 1.0 float constant input to the Tessellation slot on the material.
's the mesh (anyone can use , feel free to download it):
Unzip the file and since it is a *uasset, just copy it into your ProjectName\Content folder.
Hope that helps! I can upload the FBX if you have any issues with it, just let me know.