Downloading ProjectPlan365 25.13 for Mac from the developer's website was possible 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. The software relates to Productivity Tools. The actual developer of this software for Mac is Housatonic, Inc.
From the developer:
ProjectPlan365 lets you create new charts and modify existing project schedules in the same intuitive way as MS Project. You can open, view, save, and share your plans (MPP files) from any storage or cloud location on any Mac device. The tool works with, or as an alternative to, Microsoft Project.
You may want to check out more software for Mac, such as PitStop Extreme, 3dissue or FileOpenInstaller, which might be similar to ProjectPlan365.