Custom maps in multiplayer

Why can’t i see the button to type in URL’s for custom matches in multiplayer? I keep seeing people with a game function that i clearly do not have and it confuses me, can anyone help me understand what i’m doing wrong because i really want to play on custom maps with my friends.

Thank you.

only players that have spend (at least) 10$/€ on WT can initiate a custom (multiplayer) game…

(no clue if only purchases on the official Gaijin store count or the Steam store as well)