OAuth2 invalid client_id

I have created web api key, so I have client_id and client_secret as well.
But when I start the authorization with the following url:
https://identity.company-information.service.gov.uk/oauth2/authorise?response_type=code&redirect_uri=[the client_id]
I have the error 400 invalid client_id?
My client id looks like an UUID (I have obfuscated it in this description): e3******---***-********1b8c

What could be wrong here?

I found the problem(s):

  1. The redirect uri list in the application key must contain the redirect uri in the request
  2. You need an existing account in the https://sandbox-identity.company-information.service.gov.uk as well if you want to use the sandbox environment