That's strange, as Samsung did allow Over The Air (OTA) updates for the Galaxy S4 to Lollipop. Maybe checking the phone settings, and doing a system update might do the trick. Then again, the update was so long ago, I wouldn't be surprised if all the carriers have since removed the update from their servers. Android phones, now, should be getting an update from their carrier every month. Most of these updates are just bug fixes and security patches, which a minor version upgrade 6 months in, and a major version upgrade 6 months later.
Now, some carriers, especially Verizon, are notorious for being slow with the updates. They'll get there, but it might take longer.
Doing some research, I will admit, I am wrong about the versions of Android being used out there! According to fossbytes.com, the latest stats they have are for April 2017, and according to them, 31.9% of all Android phones still in use can't actually run MDE! That's the share of phones that are running KitKat or earlier. Wow, color me stumped. That's a fairly large group of people that can't run this program.
https://fossbytes.com/most-popular-android-versions-always-updated/
iOS isn't that fragmented, not even close. 93.7% of the iOS devices currently in use on one website (as of midnight this morning) can run MDE. Looking at just iPhones, and that number jumps to 96.8%. So only 3.2% of the iPhones in use can't run MDE.
https://david-smith.org/iosversionstats/