Hi! I'm the developer of ProShot. At this time, 4K time lapse is only possible on devices that support taking 4K video (iPhone 6, 6+, 6S, 6S+). I'm looking into ways of offering higher resolution video on other devices, but can't say when that feature will become available.
You are still able to capture 1080p timelapse video with very minimal compression, and the full suite of manual controls (ISO, shutter, focus, etc) on both the front and rear cameras