You must log in in Alibre. Then can get the photorender in the support/downloads section.
To log in you must registry to take a trial. In the Alibre webpage must give click in free trial. Via email ypu receive the password in all information to download the software (include photorender).
Now, if you is a customer, and do not have a license to use photorender must call to Alibre Support and they can generate a license demo to you can evaluate photorender.