How to configure emails on a WordPress (Ubuntu 18.04) droplet?

I’m trying to get emails accounts setup on my droplet. I am using Woocommerce (plugin) on my Wordpress site to sell products. I created a Wordpress droplet so it automatically setup Postfix for me. I tried setting up emails from the tutorials here but when I opened postfix’s config files, I saw that Wordpress had already configured it and I don’t want to mess with that because my store sends email through Wordpress.

Here’s what I have done so far:

I'm using DigitalOcean's DNS Management, I have set:
A record for example.com set to SERVER IP.
A record for www.example.com set to SERVER IP.
A record for mail.example.com set to SERVER IP.
MX record for example.com set to mail.example.com.

I’m trying to create an email address: support@example.com to use as customer support for my store through gmail. As I am not using Google Suite, I went into my other Google Account and tried to add an email address, on the SMTP field, I entered mail.example.com, then it asked me for email and a password, I am not able to find where I should configure these, or if I’m doing the whole thing right.

Can anyone here guide me to the right path?