This project, while awesome, doesn't appear to be maintained any more. It hasn't been updated for FSX although it mostly works with it.
I'll note that FSX@War has released their "Southeast Asia Pack" which contains most of the airports in the Vietnam War Project -- and it's an ongoing development project, totally FSX and P3D compatible.
Some of the advantages are that all airport objects are destroyable, and the airports have quite a low frame rate impact. In this initial package there's quite an emphasis on targets in North Vietnam and Laos. Multiple bridges and infrastructure targets, and quite a detailed target list along the Ho Chi Minh trail including, for example, Tchepone and its environment.
I myself removed the old project in favor of this one. We are basing our SE Asia missions for FSCaptain RED around it. It does require FSX@War to work, though.
Just so you know.
Dutch