Download of Navio 2.14.5509 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The application lies within Education Tools, more precisely Teaching Tools. This free software for Mac OS X was originally created by Macmillan Education Limited.
From the developer:
NAVIO provides teachers with a seamless transition between the coursebook and digital teaching activities. The application makes learning more engaging for young learners who achieve rewards by completing game-based language activities. The immersive and intuitive 3D worlds make learning fun. Students earn points and badges by completing language learning activities.
You may want to check out more software for Mac, such as ChordPhobia, EarMaster Essential or Fast Rabbit Typing, which might be similar to Navio.