https://www.cnet.com/news/fortnite-overtime-challenges-and-how-to-visit-different-waterfalls/

I'll be updating this post as new challenges unlock (Tuesday's challenges are now live and have been added). Here are the first twelve Overtime challenges (Note: The first in the screenshot is for the free Battle Pass itself).

For this one you'll have to enter Creative Mode and simply launch any of the featured islands from the Creative Hub, then search for coins.