it looks like authors gave up reading this forum. Ok.
I got the same problem, plugin doesn’t work on PHP 7.1, and I know how to fix it.
1. Open the file
\wp-content\plugins\events-maker\includes\class-query.php
2. From line 516 and below you’ll see a few (8) pieces of code like this:
$meta_args[] = array(
'key' => $keys['start'],
'value' => date( 'Y-m-d H:i:s', strtotime( $query->query_vars['event_start_after'] . $sa_date ) ),
'compare' => ($query->query_vars['event_date_range'] === 'between' ? '>=' : '<='),
'type' => 'DATETIME'
);
3. You shoud add the string
$meta_args = array();
before every string
$meta_args[] = array(
4. Save the file.
Now plugin is compatable with php 7.1
If you wanna read explanation why it didn’t work:
https://wordpress.org/support/topic/fatal-error-uncaught-error-operator-not-supported-for-strings/
Enjoy!