First check out the information you are getting from the docker log. Look at the log from the spin up and search for "kickstart." Was the container able to find the kickstart.json file? (In this case yes.)
If the kickstart file was found, continue searching through the log for a potential error in the running of the kickstart. You might see something like.
fusionauth-1 | 2025-07-02 05:14:05.177 PM ERROR io.fusionauth.api.service.system.kickstart.KickstartRunner - Failed to execute request to [PATCH][/api/user/registration/000000000001] Status [404]
fusionauth-1 | Request body:
fusionauth-1 | {
fusionauth-1 | "registration" : {
fusionauth-1 | "applicationId" : "e72dca1d-626c-4f4b-8f36-b7c8c2c0af33"
fusionauth-1 | }
fusionauth-1 | }
fusionauth-1 | 2025-07-02 05:14:05.177 PM ERROR io.fusionauth.api.service.system.kickstart.KickstartRunner - Error response:
fusionauth-1 | null
This will let you know there was an error and you need to resolve it. In this specific case, The PATCH request should have been a POST. Once that was changed, the kickstart ran fine.