Please follow the howto I referred you to.
If something doesn’t work, provide the full Nginx config you’re running as well as the output for:
mysql> select * from delivery_profile where id=$YOUR_ID;
and, ideally, a test page where the player is embedded.
Make sure it is actually using the delivery_profile.id you think it does. You can confirm that by looking at /opt/kaltura/log/kaltura_prod.log.