Ensure your device is actually on iOS 12.5.7. You can check this by going to Settings > General > About > Version .
: A newer alternative that can be installed via Safari when other apps are revoked . How to Jailbreak (Chimera/Freya - No Computer) How To Jailbreak Ipad Air Ios 12.5.7-
Because this is a jailbreak (bootrom exploit), you must understand the "Reboot Rule." Ensure your device is actually on iOS 12