I'm using a mac now. The YouTube converter on my mac is Cisdem Video Converter for Mac.
You can find the video on YouTube, add its URL to this app, then start the download.
Try this one converter https://benstoolset.com/video-converter
In my opinion, the easiest way to convert YouTube video to MP4 is using a piece of reliable software. If you are a Pc user, https://convertereal.com/ Video Converter is a nice choice. It provides the simplest approach and easy-to-use main menu for converting YouTube videos.