In PUBG Mobile, Custom Rooms are player-hosted lobbies where the host sets the map, the allowed weapons (sniper, assault rifle, etc.), and the mode (Solo, Duo, Squad). Anyone with the Room ID and password can join.

To create one, you need a Room Card.

Ways to get a Room Card

From the Clan Shop

1. Tap the Clan tab on the bottom-left of the Lobby Screen.
2. Tap the Shop tab on the right of the Clan lobby Screen.
3. Tap Room Card: 1-Use.
4. Purchase it for 300 Clan Points.

This card is one-time use only and disappears after you create the room.

From the Elite Royale Pass

• Level 14 → Room Card: 1-Day
• Level 37 → Room Card: 3-Day
• Level 85 → Room Card: 7-Day

These cards let you create unlimited rooms for the duration of the card.

Hope this helps.