So I downloaded some assets for free created by epic games https://www.unrealengine.com/marketplace/profile/Epic%20Games# But I dont know how to install them and use it when Im using the unreal engine can someone please help I would really appreciate it.

Hi When you download an asset from the marketplace it will be added to your vault. In the launcher, under the library tab you should see the content you downloaded near the bottom with an Add to Project Button.