Rendering out Orthographic Cam

I’m trying to create Physical Material mask for a landscape with an auto-landscape material. To do this, I’ve set up an orthogonal camera to replicate the Top View and wish to use this to map footstep sounds. However, when I render out a still frame from the Cinematic sequencer, it produces an image with perspective.
I’ve tried creating a new camera from the sequencer, but there is no way to change the lens to ortho there.

Am, I going about this the wrong way? Is there an easier way to capture a top down view of my map to create a mask?
The original Heightmap is no good because the landscape has been sculpted since import.