As part of your Fortnite Crew subscription, you receive Battle Pass in Fortnite as one of its perks. If you have already purchased the Battle Pass separately, you will receive an additional 950 V-Bucks.
The additional 950 V-Bucks are only for players who purchased a season Battle Pass before subscribing to Fortnite Crew. The additional 950 V-Bucks are to cover the cost spent on the current Battle Pass which is included with your subscription. It is not a recurring monthly bonus.
You will also receive 1000 Credits in Rocket League if you already purchased the current Season's Rocket Pass Premium before subscribing to Fortnite Crew during that Season.
Note: This is a one-time payment if you purchased a Battle Pass before the Crew subscription. It is not a recurring monthly bonus.
If you did not already own the Battle Pass when subscribing to Fortnite Crew, you will not receive an additional 950 V-Bucks credit.