Total Upkeep Fatal error Class ‘Boldgrid\Library\Library\Ui\Card’ not found

Hi there

I did a fresh install of WP today and Total Upkeep was one of my first plugins to install (downloaded directly from the Boldgrid site) – for some reason I seem to be having issues with a fatal error:

Fatal error: Class ‘Boldgrid\Library\Library\Ui\Card’ not found in /home/XXXXXXX/public_html/wp-content/plugins/boldgrid-backup/admin/card/class-amazon-s3.php on line XX

I have googled this and followed an previously resolved issue here: https://wordpress.org/support/topic/fata-error-when-trying-to-activate-total-upkeep/ but I was unable to change the lines on Option Inspector as the original poster did.

Any help gratefully appreciated

Nacela