Cannot download Security Key app Android

I recently been wanting to get back into the game and thought it would be a good idea to set up a security key, however i cannot download the app, every time i go to the Google play store page it gives me a warning a long the lines of the app is for a older version of android or something. checking the last update for the app it was apparently last updated in 2015. is it not possible to download the app anymore for android phones unless you have a phone with an older version of android?