This error says that you do not have permission to write to this file. There are two easy solutions to this problem:
Go to the file it specifies and check the permission. To do this right click on the file and select Properties. Check the Attributes to see if the file is Read-only. Then, click on the Security tab to check if your computer is one of the user names with access to the file. This should give you more insight on why you don't have permission. Sign on as an administrator. The administrator should have full access to all of the files you need to write to when installing SEPM