Basically, you have to tag first all entities of the "going to" environment with the ids of the corresponding entities of the "coming from" environment. Once all entities are tagged in production site with the development site ids, the program allow to automatically transport the following entites :
App
SystemRule
DataConnection
ReloadTask
Stream
CustomPropertyDefinition
Tag
You have to play the script a first time on the development environment to create the packaging, a folder called release. Then you have to copy and paste the folder on the production environment. Then play this release folder on the production environment to get all the entities that you transported on the production site.
During the packaging, some check are made into the application (the presence of exit script for instance) to help developpers having a good release quality.
The authentication of the program is based on the user NTLM rights, which means you have to go on the machine to make it work and users that have no rights in Qlik Sense are unable to play the script. It is a secure way of making the release.