Premium version fatal error attempting to activate

The free version of FG Drupal to WordPress worked but when I purchased and installed the premium version (via add new plugin, uploading the zip file provided) I am getting the following error when attempting to activate it.
Parse error: syntax error, unexpected ‘[‘, expecting ‘)’ in /home/redacted/public_html/wp-content/plugins/fg-drupal-to-wp-premium/public/Crypt.phpon line 57

I have contacted their customer support

• This topic was modified 8 years, 2 months ago by sophiavancouver.
• This topic was modified 8 years, 2 months ago by sophiavancouver. Reason: redacted private info