4-digit passcodes are only given as part of a Details Blog when you have been booked for work. Often, the first text message you receive from a Casting Director is just an availability check. You'll know you're booked when you accept an offer for work and are given Details. Our article "How to text with a Casting Director" has more detailed information on the texting process. https://www.centralcasting.com/first-avail-text-with-casting-director/
I would suggest to check your email. Also the spam folder. Usually communication about set times, locations, costuming and make up direction is done through there. If you don't receive any info by the day of the shoot (i.e. commercial extra, stand in, singer/dancer, etc..) then you haven't been cast.
If they didn't book you you won't get any additional information. You'll get a text saying you're booked and giving you the next steps. If you did get a text saying you're booked but never got your details you should have called them. Also, there isn't a 4 digit passcode.
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