Cleaver 1.16.3 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. This free software for Mac OS X is an intellectual property of Clever Inc. We recommend checking the downloaded files with any free antivirus. The software lies within Education Tools, more precisely Teaching Tools.
From the developer:
Clever is your school’s digital learning platform, one friendly place for resources, communication, and instruction. With single sign-on, everything is one click away for students, families, and educators. It works the same everywhere, so your community is remote-resilient.
You may want to check out more Mac applications, such as BeatCleaver or Grindstone, which might be related to Cleaver.