Should be able to get a copy through an App Store link
here:https://support.apple.com/en-us/HT208969 Under step 4 - Get macOS
The reason it's reporting as damaged is...
I'm using RHEL 7 server to run our JSS clustered instance in a vCenter
setup. They are all setup with XFS root file systems with the JSS
installed to the default directory (/usr/local/jss). The root FS is only
15GB and that leaves ~6GB free at worst ...