My problem is MP4 at 4k is not available.I tried to download the same video (https://www.4kdownload.com/de/howto/howto-download-youtube-video) but only 1080p is working.
YouTube stores several formats and resolutions of a video, which 4K Video Downloader parses and downloads. YouTube has changed the way content is stored. As a result, 4K resolution can be downloaded only in MKV format for the moment.
Please change MP4 to MKV format to get 4K Resolution.