Hi! You’re not allowed to use backgrounds from Pinterest as majority of them are copyrighted. Unless you do thorough research and find out who the owners are and get permission from them.
I know it sucks. And episode usually approves backgrounds as long as it doesn’t look obvious that it’s copyrighted (watermarks and logos).
My best advice would be to use backgrounds that people have made for episode or use free sites such as pixabay and unsplash 