Ghostscript should have been installed when HFM was installed. It is part of the installation unless your location chose to have Adobe Acrobat as the PDF engine generator. By the way in the context of this question, ghostscript is something that is installed only in the HFM/EPM server infrastructure.
I believe that the issue is with the security privileges on the folder that the report is created. The folder can be something similar to: D:\Oracle\Middleware\User_Projects\EPMSystem1\products\FinancialManagement\Web
If you search MySupport, you will find an article with the name of the windows folder that you should grant access to the user Everyone.