Hello, Volchonok
To access Paper Sprite, Paper Flipbook and other Paper2D classes please go to Plugins/2D/Paper2D/Classes.
Also, please don’t forget that in order to use Paper2D, appropriate module should be added to Build.cs file of your project (YourProject/Source/YourProject/YourProject.Build.cs):
PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "Paper2D" });
If you like to learn more about Paper 2D Components, please go here:
Hope this helped!
Good luck!