Microsoft Graph - How to get App to read user calendar events - microsoft-graph-api

Question

I'm trying to create a Node/Javascript service that will read a user's outlook calendar.
This took about 2 hours to get the front and backend fully setup and working with Google Calendar.
I'm on my 2nd week of trying to get this to work with Microsoft Graph.
The user giving authorization will be outside of my app's tenant/organization.
I've registered an app in Azure, and given it the Calendars.ReadWrite and Users.Read permissions.
I've granted Admin consent for the default directory (someone suggested this).
I've setup the front end authorization page for the user to give authorization for the app permissions defined in the scope.
The front end user authorization works fine, the authorization page pops up describing the access that the app is requesting and on confirmation it returns the user's access_token, refresh_token, does the redirect, etc.
The part I'm having the problem with is for the Node application to read that user's calendar events.
Depending on whether I add the user's accessToken to the call, I get different errors returned.
I have created 2 functions so far in the Node application.
The first function getMSClient populates the authProvider with clientId, clientSecret, tenantId, and gets/returns a client with the authProvider information
This function "seems" to be working fine. If I do an output of the client I get an object with config: {...lots of properties}
The second function is where I'm trying to make the call to read the user calendar, but I get all sorts of errors,
If I use the client and make the call with:
const events = await client.api(users/${email}/calendar/getSchedule).get()
I receive an object with a statusCode of 401
If I use the client and add the user's accessToken to the header and make the call with:
const events = await client.api(users/${email}/calendar/getSchedule)..header('Authorization', Bearer ${userAccessToken}).get()
I get an error message about 'CompactToken parsing failed with error code: 80049217'
with 401 statusCode and code 'InvalidAuthenticationToken'
Here is the code:
const getMSClient = async () => {
const credsJSON = await fs.readFile(CREDENTIALS_PATH);
const creds = JSON.parse(credsJSON);
const {tenantId, clientId, clientSecret } = creds;
const credential = new ClientSecretCredential(tenantId, clientId, clientSecret);
const authProvider = new TokenCredentialAuthenticationProvider(
credential, {
scopes: ['https://graph.microsoft.com/.default']
});
const client = await Client.initWithMiddleware({
debugLogging: true,
authProvider
});
return client;
}
const getAllEvents = async () => {
const userAccessToken = 'eyJ0eXAiOiJKV1QiLCJ .........';
const email = 'user#outlook.com'
const client = await getMSClient();
const events = await client.api(`users/${email}/calendar/getSchedule`).header('Authorization', `Bearer ${userAccessToken}`).get()
console.log(`events: `);
console.dir(events)
}
getAllEvents();