There is always a risk if you install something on your system that you didn't read and understand the source code. That said, installing a distributed computing application is not more dangerous than downloading a text editor (if the source can be trusted). A distributed computing application does not need to have access to your files, all it needs is access to the system resources and the internet.
So if you want to be on the safe side, you can have it run under a very limited user account or even in a virtual machine but usually that should not be necessary on a private computer. On a work computer I would not recommend installing anything which is not necessary as there is always a risk that the program, even if not designed that way, misbehaves ;-).