Hi Lynn,
Only email could be synced if you add Gmail as mail server in CRM. Find the supported records type here.
I tested and got success with this tutorial. But I still met some troubles and I'm glad to share solutions and notes:
1. In Gmail setting, the link that Allow less secure apps is wrong, please replace it with this corrected one:
https://myaccount.google.com/lesssecureapps
2. My testing Gmail is personal account(xxx@gmail.com), the Outgoing port 465 in the article got failed in my test process(Google may has changed it),
please replace it with port 587, I got this solution from official support.
3. I only got totally sucess after I set both Incoming and Outcoming Emails to SSS(At beginning, I only enable Incoming option, Test&Enables worked and got success status, but I still failed to receive emails)
4. Be aware that Appointmens,Contacts and Tasks should be set to None or D365 for Outlook.
5. You will receive a success configuration email in your Gmail inbox(sender is your Gmail itself).

Result for sync:
In my another email account:

In CRM

Finally,this post is helpful if you met any trouble in setting up process.
Regards,
Clofly