In general words you need to create a project (or use an existing one) and create a new client type saml. There you should have the option to edit a file with needed parameters.
Currently we do not support idp initiated, but you can define a default redirect target which could be your app which in turn creates a sp initiated flow.
Hi @Xavier R not quite sure on what would have helped you here, if you can elaborate a bit, would it have made your process easier if you had the information on the scopes also on the introduction page?