Get events of a certain category

I tried to retrieve events of a certain category, but it won’t ever return any results.

1. What category name is to be used? For instance, there’s a category name (e.g. “Twitch Streams”) and a category ID which is also part of the category URL (e.g. “twitch-streams”)
2. I tried different ways to code the query, here’s one example. Could you kindly assist me in correcting whatever is wrong? Thank you.

$events = eo_get_events(array(
'numberposts'=> $NumberPosts,
'event_start_after'=>'today',
'tax_query'=>array( array(
'taxonomy'=>'event-category',
'operator' => 'IN',
'field'=>'slug',
'terms'=>'twitch-streams'
)),
'showpastevents'=>true
));