I got it from their tech. support a while back.  I think it's similar to 0.7.6 with added support for extensive debug printout put nicely into a tarball so you can (could) email it to CT.  I don't think CT cares so much anymore.  

Someone had a set of links to all the firmware versions on the CT forums, before they took them down.

They were all up on GitHub too but I'm not sure if they still are.  The devs may have wised up and put them into a private repo.

I suspect if you email support@cointerra.com they might still send it to you.  Who knows.