Some networks require you to update to 4G sim card to enable this feature. Yet other networks need you to sign up for a 4G plan before you can receive 4G.
Besides, it looks as though Meditel are only just beginning to roll out 4G in certain areas of Morocco. Check if you need a 4G sim card or need to sign up for 4G or can receive 4G in your local area. You will need to contact Meditel directly.