If it’s something mission critical, consider following the 3-2-1 backup rule.

I tend to use whatever built-in snapshot option the service provider offers, and then for off-site backups can use something like Veeam (free for first 10 VMs / machines) - https://www.veeam.com/virtual-machine-backup-solution-free.html

Sounds like what you want is some form of webhooks that your customers can sign up for, that will send out when the reports are complete.

There are quite a few ways to do that. One I’ve looked at recently is Convoy, for setting up a user-facing webhook Dashboard -

https://getconvoy.io/

By using webhooks for delivery, then your actual configuration / viewing of schedules just becomes standard API calls.