I have installed Snapshot Pro into thill.com.au - I also installed the plugin you supplied - I updated the wp-config.php with the exact settings you used for sydneypropsphotostudios and put in exactly the same file exclusions you did - however all backups fail at about 51%
I don't think I will be able to get this working for my other sites at VentraIP - maybe it is a limitation of the shared hosting they have.
As mentioned previously with sydneypropsphotostudios we are paying for additional resources.
My other clients are not prepared to pay for more resources.
I noticed that it appears the backup has been successful for https://sydneypropsphotostudios.com.au/ - there is a snapshot visible. Has it correctly backed up? If so, what settings do I need to change to get Snapshot working on all of my VentraIP sites?