Backup to Dropbox worked, but doesn’t show in latest

I have my Updraft Plus set to backup to my Dropbox account. According to the existing backups listing in WP and my actual Dropbox folder, I have a complete backup as of today, but I had to manually do it because my host required me to have WP CRON disabled due to CPU issues. They created a custom CRON script for me, but it seems as if Updraft can’t use it automatically. I also tried to do it via WP-CLI, but I got error messages about not being able to find the cPanel Quota Usage, and “errno 32 on write.”

As a result of WP CRON being disabled, I see “Warning: WordPress has a number…of scheduled tasks which are overdue. Unless this is a development site, this probably means that the scheduler in your WordPress install is not working.” and “Warning: The scheduler is disabled in your WordPress install, via the DISABLE_WP_CRON setting. No backups can run (even “Backup Now”) unless either you have set up a facility to call the scheduler manually, or until it is enabled.”

So a few questions:
(1) If I have to keep WP CRON disabled, how do I set up the custom script I have from my host to “call the scheduler manually?”
(2) If I have ALTERNATE CRON set, will Updraft not see that? (Is ALTERNATE CRON even be appropriate in my case?)
(3) What does “a facility to call the scheduler manually” mean, if not another script that allows WP Cron jobs?
(4) Why would I also see “UpdraftPlus Vault: this site has not been connected – check your settings” if Dropbox is connected and clearly receiving backups? I’m not using UpdraftPlus Vault!

I used WP Crontrol to see what all the tasks were, and most of them are normal, everyday cron tasks from various plugins. There doesn’t appear to be any one plugin that’s creating too many tasks, so I don’t know what the holdup would be.

The “latest scheduled backups” listed at the top are from January, so it seems like part of Updraft isn’t seeing my Dropbox backup from today, and may even be keeping part of a backup locally (web-server disk space in use).