There is a .dmg of the software installer for "JAMF Composer" on Software
Log into JAMF Nation
https://account.jamf.com/
JAMF ID for Jamf Nation
Put in your UN and Password
https://account.jamf.com/products/other/composer/download
When Logged in click on Products>Add Ons> Composer > Choose Download
Drag this over to the applications folder and open it