Even though Jamf has its own package creation tool (Jamf Composer), there are lots of great reasons to use munkipkg instead for creating custom packages, as Elliot Jordan outlines in You might like MunkiPkg.

One of the keys munkipkg has is the distribution-style key (more details in the munkipkg README), which is usually fine to leave as false.

But if you’re using a package for PreStage Enrollment, it has to be both a code-signed package and a distribution-style package (read more in Jamf Pro Documentation).

So all you have to do (apart from code-signing), is change the build-info.plist file from having

<key>distribution_style</key>
<false/>

to having

<key>distribution_style</key>
<true/>

Then rebuild your package and upload it to Jamf Pro.