Which casting call company is that? There are many in different countries.
If you mean some online thing, it's probably fairly legit, but it won't find you any real auditions for serious acting jobs. They're found through real agents. If it asks you to pay to join, it's probably not worth it.
You might find auditions for extra work, adverts, amateur stuff, touring theatre companies, promotional work, student films, etc. But most of it is unpaid or very low paid.