New update complete broke website with PARSE ERROR

Hello. I am on WordPress 4.3.1 (4.4 sucks).

When I updated to the latest version of the MyEffecto plugin, it gave me the following error website-wide:

Parse error: syntax error, unexpected '[' in /home/soyeg992/public_html/sudbury.club/wp-content/plugins/instant-feedback/DBFunctions.php on line 150

So I was forced to rename the plugin folder and disable it to fix the issue.

Do you know why this happened?? Am I the only one?! :O

https://wordpress.org/plugins/instant-feedback/