Secure Storage 2 is still in development. Until we release a stable version please use SecureStorage 1

Secure Device Storage - Android

Storing Credentials Securely on Android Devices

In any case, SecureStorage 1 will not be deprecated even after SecureStorage 2 has its first stable release. Development will be continued also on SecureStorage 1 - there are only some things like Symmetric Encryption which we only support with SecureStorage 2