Here is a guide which might be helpful. https://www.ezcast.com/res/Google-Home-Assistant-manual-V2.pdf

First off, you need to connect to the device before you enter EZChannel if you were using EZCast app.
And the device must not be registered by another user.

Hello, What is the app name you were using? Android or iOS app?

Hi there, which password are you referring to?