create app based service principal auth token using nodejs

I'm trying to create app based service principal authentication token using Node JS. I'm able to get token(not sure it's service principal token) able to pass in header as Auth bearer token able to get Embed URL While running embed URL getting Sign in page, what is the issue ? I'm using below code :

/*authentication.js */ 
async function getAuthenticationToken() { 
var adal = require('adal-node'); 
var AuthenticationContext = adal.AuthenticationContext; 
var context = new AuthenticationContext(authorityUrl); context.acquireTokenWithClientCredentials(config.resourceUrl,config.appId,config.clientSecret, function(err, tokenResponse){
 if (err) reject(" ~ "+err);
 resolve(tokenResponse); 
}) 
}
 /* index.js */ 
var auth = require(__dirname +'/authentication.js'); 
tokenResponse = await auth.getAuthenticationToken(); 
var token = tokenResponse.accessToken; 
var resd = await utils.sendGetReportRequestAsync(requestParams.url, requestParams.options); 
var embed = resd.embedUrl+"&autoAuth=true";