Server error when first launching WorkflowGen after installation

When launching WorkflowGen for the first time after installing it, you might receive the error:

Server Error in '/wfgen/' Application, with the message CS0016: Could not write to output file '[DRIVE:]\Windows\Microsoft.NET\Framework[64]\[VERSION]\Temporary ASP.NET Files\...

This is due to security permissions on the Temporary ASP.NET Files and [DRIVE:]\Windows\temp folders. To solve this issue, navigate to each of the folders, and assign full control permissions to the IIS_WPG, IIS_IUSRS, and NETWORK SERVICE users.