The app is Clime Pro on iOS, they lock full access to Hurricane Milton data behind a $10 USD per week paywall.
If you’re in the area impacted by Milton, you can find publicly available resources at the National Hurricane Center’s website: National Hurricane Center
Ryan Hall is doing a Livestream on YouTube providing all day coverage of the hurricane. Several cameras up in areas that will receive the worst of it. Several meteorologists on staff, radar info and explanation, storm chasers on the ground. Pretty much all of the information you could need. Link