It is not uncommon for alpha and beta builds to break save files.
Meaning, that if you try to use those save files later, in the full release, it might make the game crash.
For that reason, Runey does not post beta builds here.
And a lot of people are happy with that decision.
Because if they were posted here, then the regulars would have to deal with the screaming from people who were trying to use those save files that were created in the beta.
And possibly things that won't even show up in the full release, because the testers, who are the ones who have access to the beta builds, know not to make save files, and already reported the problem.
Not to mention the fact that if you played the beta, you would have to play the full release of it anyway, because content may have been added or changed, that was not in the beta.
Which is one of the issues that can lead to broken save files.
Beta builds: A test to see if things are working out the way that the dev wants them to.
If they don't, then things get changed, and save files are broken...