Worldwide Webb and Soulbound are two names for the same game. Over time, the Worldwide Webb branding will be replaced with Soulbound branding, and everyone playing Worldwide Webb will automatically be transitioned to a Soulbound account.
Worlwide Webb is available to be played at https://play.webb.game . You will need access as described here to play it.
Soulbound can be played through July 11th, 2024 as a Discord Activity in Discord Town Hall. You will need a Discord account to play this.
Further into the future, the Soulbound experience and the Worldwide Webb experience will be merged, including features, dungeons, enemies, and quests from both games.