Fatal error when trying to add Amazon S3 destination for snapshot

Hello,

I am getting ready to make some big changes on my site. Before doing so I want to make backups. Is snapshot the right tool for this?

If so, can you please help me with this error?

Fatal error: Undefined class constant 'REGION_US_W2' in /home/niklun/nikkislessons.com/wp-content/plugins/snapshot/lib/destinations/aws/index.php on line 81

Thank You,
Nikki