Can you please confirm that you are using JetBackup for WordPress, and not Jetpack? To provide clarification, this is a separate plugin, and if this is the plugin that you are using you can find their support threads here: https://wordpress.org/support/plugin/jetpack/
After uninstalling and installing the plugin I can click on the button to upload a backup. But the upload of the backup is very slow, not sure if it will work.
Can you please try updating to the latest version, v2.0.7, and see if the issue still persists? You can do this by opening WordPress admin -> PLugins -> click on auto-update for Jetbackup plugin and update. Thank you!