ERROR: Please select at least one of the signature versions to use

You can click on the "Signature Help" link next to it for more information:

Android 7.0 introduces APK Signature Scheme v2, a new app-signing scheme that offers faster app install times and more protection against unauthorized alterations to APK files. By default, Android Studio 2.2 and the Android Plugin for Gradle 2.2 sign your app using both APK Signature Scheme v2 and the traditional signing scheme, which uses JAR signing.

Although we recommend applying APK Signature Scheme v2 to your app, this new scheme is not mandatory. If your app doesn't build properly when using APK Signature Scheme v2, you can disable the new scheme. The disabling process causes Android Studio 2.2 and the Android Plugin for Gradle 2.2 to sign your app using only the traditional signing scheme.

There're also a few topics at Stack Overflow, such as this one, which recommends checking both of them if possible and unchecking V2 if it gives you issues:

It is a new signing mechanism introduced in Android 7.0, with additional features designed to make the APK signature more secure.

It is not mandatory. You should check BOTH of those checkboxes if possible, but if the new V2 signing mechanism gives you problems, you can omit it.

So you can just leave V2 unchecked if you encounter problems, but should have it checked if possible.