https://www.gamespot.com/articles/xbox-one-pubg-test-server-comes-back-online-here-a/1100-6460328/

PUBG Corp. has released a new update for the Xbox One version of PlayerUnknown's Battlegrounds. The PUBG test server (PTS) is once again live, and there's a ton of new content for players to try out. The server will remain open to all Xbox One PUBG players until July 16 at 1 AM PDT / 9 AM CEST.

The PTS is an entirely separate download that puts you on a temporary server. You need a copy of PUBG on Xbox One to play it. The server's primary purpose is to test new features and maps prior to officially launching on PUBG. PUBG Corp. previously launched the PTS to test load times, item and vehicle placement, and player behavior on Miramar prior to the map's launch on Xbox One.