$rfg_ids = toolset_get_related_posts( $post_id, 'repeatable-group-slug', 'parent', 100, 0, array(), 'post_id', 'child');
if ( $rfg_ids ){
foreach ( $rfg_ids as $rfg_id) {
$url = get_post_meta( $rfg_id, 'wpcf-repeatable-field-slug', true);
...
}
}
$post_id The post id of the query post
100 LIMIT, maximum number of returned results (“posts per page”). Default value is 100.
0 OFFSET, result offset (number of post to displace or pass over). Default value is 0.
array() Additional query arguments to narrow down the search.
post_id Determines return type. ‘post_id’ for array of post IDs, ‘post_object’ for an array of WP_Post objects. By default, post IDs are returned.
child role_to_return: Which posts from the relationship should be returned.
Detailed explanation: https://toolset.com/documentation/customizing-sites-using-php/post-relationships-api/#toolset_get_related_posts