misunderstanding in enviroment

[Việt Hưng Nguyễn]

Sorry, I have clone your repository to learn because I also have to implement keycloak into NextJS (using SAML protocol). I can run your project, but when I click button login, it redirected me to keycloak but it's the page not found. So I think I missing a step?.
I think the problem in enviroment in this code below

export const idp = samlify.IdentityProvider({
	metadata: Buffer.from(process.env.IDP_METADATA as string, 'base64'),
});

export const sp = samlify.ServiceProvider({
	entityID: process.env.SP_IDENTITY,
	authnRequestsSigned: true,
	wantMessageSigned: true,
	wantLogoutResponseSigned: true,
	wantLogoutRequestSigned: true,
	wantAssertionsSigned: true,
	signingCert: Buffer.from(process.env.SIGN_B64_CERTIFICATE as string, 'base64'),
	privateKey: Buffer.from(process.env.SIGN_B64_PRIVATE_KEY as string, 'base64'),
	privateKeyPass: process.env.SP_PRIVATE_KEY_PASS,
	assertionConsumerService: [
		{
			Binding: samlify.Constants.namespace.binding.post,
			Location: process.env.SSO_CALLBACK_URL as string,
		},
	],
});

I don't know how to get base64 certificate and private key, private key pass ( sorry but all of this enviroment above =))) I researched but it have many source but none of them give me a solution, that's poor )
So could you tell me where you get private key, certificate also metadata in keycloak.
By the way, I was struggling to find a good tutorial on this, but your approach is actually well thought out. It's very nice and very helpful