The pdf doesnt say anything about picking a terrain though it just says natural world, that is why I didn't put one.
OOC:
You are a master of navigating the natural world, and you react with swift and decisive action when attacked. This grants you the following benefits:
• You ignore difficult terrain.
• You have advantage on initiative rolls.
• On your first turn during combat, you have advantage on attack rolls against creatures that have not yet acted.
No worries, take your time.