From where to download APK for Testnet?

I’ve tried to download from the link suggested from F(x) Core validator node setup on f(x)Core Testnet - #90 by Mdmdmd83, however Android doesn’t let me install it. I’ve checked Install unknown apps section, but I don’t see that app there.

Error: App not installed.

Is this the right APK? Or do I need to change some settings?

The same happened to me. You can’t have both versions on the same terminal (regular FxWallet and beta) on Android.