Tried on Oneplus 3T running on Android 8.0. The application didn’t show up on Play Store so I downloaded the APK version and there seems to be an error when parsing the package when trying to install.
Edit: Tried it on Samsung Galaxy Tab S running on 7.1.1 and it doesn’t install too.
I’m not sure that you heard that Google Store only allows apps whose API level is 28 or above. It means your android version should be Android 9. 
If you want to use it under Android 8, please check http://mudfish.net/releases/ link and try to install other APK files.
From what I know about Android app development, the minimum required API level can be anything, what Play Store is enforcing is Target API level which is the level that you have tested the app and the app shouldn’t have any issue on that API level. 4.4.25-26 seems to work fine on Android 8 though.
Edit: https://developer.android.com/guide/topics/manifest/uses-sdk-element.html#min for more information about the Target API and Minimum API level