Hi,
Unity told you to open it with a beta version?!? this is really bad... Unity beta are not stable nor supported properly by PlayMaker until it goes public, so this is not. a good idea indeed...
a project should that worked, will always work if you don't change the unity version with which you worked with it, so I would go back to the first step and chekc why this project doesn't work anymore.
also: you need to clear up all the errors, the first error is not related to PlayMaker. Unity and PlayMaker do not work properly until all errors from the Unity console are gone,
Bye,
Jean