Use the import function in the Unreal Engine editor or drag and drop the Aseprite file you want to load into the content browser. Importing an Aseprite file will generate the following assets:
Flipbooks > Flipbook Assets
Note: When using the Split Layers option, a flipbook is created for each layer in the Aseprite file, based on the Visible Layers
Frames > Sprite Assets
Textures > Texture2D Asset
If you've made changes to the original Aseprite file after importing it and wish to reflect those changes in the Unreal assets, you can simply execute the Reimport option for the Aseprite file, as shown in the image below.
Note: Due to the limitations of Paper2D, which does not support direct keyframe editing, Flipbooks cannot fully utilize the Reimport functionality. If there are changes to the Flipbook itself, such as the addition of animation frames, you will need to create a new Flipbook using the 'Create Flipbooks' menu option.