Setting up a private server is rarely a "plug-and-play" experience. It requires a decent understanding of networking, database management, and sometimes reverse engineering. 1. Source Code and Leaks
This is the backend software required to make the game run, process accounts, calculate physics, and host races.
Are you looking to for yourself, or are you looking to join an existing private server?
Hosting or distributing game files for a game that is still actively licensed and operated (like Tales Runner in various regions) violates copyright law and the game's Terms of Service.