This article explains how to set up an SRX device with a ZTP server without needing any manual assistance.

Please refer to the document below to learn about how Zero Touch Provisioning works and its limitations: 

Understanding Zero Touch Provisioning on SRX Series Firewalls

If you are using a custom ZTP server to set up your SRX automatically, make sure that the configuration has no syntax errors. If there are any errors, ZTP will not be able to apply the configuration to the SRX.