The 2.1.0 version of ASO for Mac was available to download on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. This free Mac application is a product of 2Stable. The software lies within Developer Tools, more precisely Webmaster Tools.
From the developer:
ASO is an application for iOS developers. It provides you with the tools required to create, test and analyze your app performance so you can improve your app visibility on the App Store. You can easily track your App Store rank and visualize any changes. You can analyze top charts on iPhone, iPad, Mac and Apple Watch.
You may want to check out more software for Mac, such as Bank2QBO, Bank2OFX or Coupert for Safari, which might be similar to ASO.