Alright, let's get started! First things first, you need to set up a SAML project in your identity provider's console. The steps might be a bit different depending on which provider you're using, but generally, you'll need to grab a few key details like the SSO URL, Entity ID, and a public certificate.

Next up, head over to the Firebase Console. Navigate to the Authentication section, then click on "Sign-in method" > "Add Sign-In method" > "SAML". Easy peasy, right?

Now, in the Firebase Console, you'll need to enter the details you got from your SAML provider. Here's what you do:

1. Pop the SSO URL into the "SSO URL" field.
2. For the "Entity ID", just input the Entity ID from your SAML provider.
3. Paste the public certificate into the "Public certificate" field.
4. Set up the Service Provider details - an entity ID and a callback URL. The entity ID can be any URL and doesn't need to resolve to an actual address. The callback URL will auto-populate and should be added to acceptable callback URLs in your SAML provider's settings.

Note: The URL doesn't have to point anywhere. It just needs to be unique for each provider.

Finally, hit "Save" to wrap up the setup.

Now that your SAML provider is all set up, it's time to implement Firebase Authentication in your web app. You can either use Firebase UI to handle the sign-in flow or manually launch a sign-in flow using JavaScript.

Here's the code to get you started:

var provider = new firebase.auth.SAMLAuthProvider('saml.myProvider');
firebase.auth().signInWithPopup(provider)
   .then((result) => {
     // User is signed in.
     var user = result.user;
   }).catch((error) => {
     // Handle Errors here.
     var errorCode = error.code;
     var errorMessage = error.message;
   });

In this example, replace 'saml.myProvider' with the provider ID from your Firebase console. This code launches a sign-in flow when called and then signs in the user.

Now, your end-users should be able to sign in to your application using their SAML credentials. The user's SAML attributes will be available from firebase.auth().currentUser.providerData[0].

Note: Firebase Authentication doesn't handle user profile creation or role assignments, etc. Typically, you'll need to create a Cloud Function to handle these tasks when the user first signs in.