Assuming your “category” field is a taxonomy field and the return type is term_id. then you can try:
$events = tribe_get_events(
array(
'eventDisplay'=>'upcoming',
'posts_per_page'=>-1,
'tax_query'=> array(
array(
'taxonomy' => 'tribe_events_cat',
'field' => 'term_id',
'terms' => get_field('your_category_field_name')
)
)
) );