Question How to change StreamingRender Html and the number of cameras

hello
I am new to Render Streaming
(Unity version: 2019.3.14f
RenderStreaming version: 2.0.2)

I copied the scene of the Sample Project that was created after downloading the Render Streaming package.

After that, I changed the object and Sky value of the scene.
And I deleted one of the two cameras in the scene.
(I only need one camera.)

I accessed localhost
But the screen didn't come out.
(Only the button has been operated.)

I'm curious about these two
1. Do I need two cameras to use Render Streaming?

2.Generated when played on localhost
Button, can you modify or remove the image ?
(I pressed F12 and it seems to be HTML value, but I don't know how to approach and modify it.)

Help me...
thank you.