Back up emails (gmail)?

Hi dear NAS experts,
I’ve got my new DS220+ a couple of days ago. As a total newbie to the world of backups and Synology I’m getting a bit overwhelmed when I see the many apps offered to the user in the Synology download center.
I wanted to back up mostly all my gmail emails. My first attempt: Active Backup for G Suite. I haven’t make it further than the first screen on the assistant. There I’m asked about a “domain for backup”. What is this or where do I find this in my Synology control panel/setup?
Later on after searching on more information about this topic I noticed there is another Synology app called Cloud Sync. So what is the difference with Active Backup? I think a sync is more convenient to me as once I get to download my emails to the NAS I will surely purge a lot of junk and I’d like to mirror this changes back to gmail.
Have you perhaps already written any article on the topic “CloudSync vs. Active Backup”?
(My next cloud based backup after gmail will be Office 365)
Thanks in advance for your help!

Active Backup for G Suite will back up your G Suite, including Gmail. But you need to be a Gsuite user with an account. If all you have is simple Gmail, then there will be no way to back this up. https://workspace.google.com/intl/en_uk/CloudSync will allow you to sync your cloud drives with your NAS such as google drive/ dropbox etc.Active Backup will back up your Computers, VMs, Servers.Synology Drive will replace Dropbox. Google drive. This will be your private cloud. You can also back up Windows and MAC.TimeMachine will back up your MACs.I hope this helps.