plugin won’t install

I’ve tried installing the WordPress MailerLite Integration Lite plugin in both ways suggested and each time I receive the following message:

Parse error: syntax error, unexpected ‘[‘ in /home/sites/draw4profit.com/public_html/wp-content/plugins/wp-mailerlite-lite/includes/vendor/guzzlehttp/psr7/src/functions.php on line 78

Based on a quick glance at the file the line in question reads:

function stream_for($resource = ”, array $options = [])

Can you tell me what to change to install your plugin?

Thank you.