Well established and ready to function
After the parts of something are in their proper position and function properly, they are set up.
When an activity or project is planned, arranged, or organized, it is set up.

1. To begin, or enable someone else to begin, a venture by providing the means, logistics, etc.
2. To get ready for a particular purpose or event; SYN. lay out. setup, set-up

When you arrange the parts of something so that they are in their proper position and can function, you set it up.
When you plan and organize an activity or project, you set it up.