No! TestFlight is an iOS only thing, Android would have its own way of enrolling in a beta, or just installing the .APK directly. Whatever you found is definitely shady.
TestFlight is an Apple thing. There are ways to install Android apps that arenโt in the Play Store that the dev could use, but not by that name. Especially if it looks shady, stay well clear. Iโm afraid I use an iPhone so I canโt help with more specific details on how to install this specific app.