EPOS will not be updated anymore, as it's been replaced by Odyssey: https://praxinos.coop/odyssey.php

Extended Production Of Storyboard - or EPOS - is a storyboard manager plugin in Unreal Engine Editor. EPOS is designed for 2D storyboard artists ; its use is simple and intuitive, yet powerful and complete : use 3D environment and create shots, cameras and planes in a few clicks directly from the Sequencer. Adjust the angle and the perspective, enable the plugin ILIAD and you can start drawing!

EPOS is source-control and multi-user compatible: storyboard artists, previz artists, background artists, film directors and all other people involved in preproduction can work together in real-time to share and enhance their vision of the art.