Changing content of zip causes a permission failed

I had a working version of this project, but whenver I try to change the contents of the zip file (the jasperreport server zip file) I get the error:

/entrypoint.sh: line 57: ./js-ant: Permission denied the first time and /entrypoint.sh: line 66: ./js-ant: Permission denied the second.

(the lines being "init-source-paths " and "./js-ant $i " respectively)

I want to change the js.quartz.properties file like in: https://community.jaspersoft.com/wiki/configuring-report-scheduler so that the dockerised server can send emails.

doing that or just any change, like adding an empty .txt file or deleting a file in the zip folder will start making permission denied errors.

I'm thinking editing the zip file, somehow changes its rights, but I made sure to give all files execution rights with chmod -R 777

I've added the RUN chmod +x /entrypoint.sh from the readme, but it didn't help.

I work on windows, with version jasperreports-server-cp-6.3.0-bin of the server .

github link to jaspersoft for docker: https://github.com/TIBCOSoftware/js-docker