My Last Hope

Hello All, I have been reinstalling my add ons for P3D but there is one that I need help with. The add on is World Ground Traffic, it adds service vehicles to P3D. It says that it works for P3D v2 and I thought I installed it correctly but the vehicles don't show up in the sim. I have tried sending an email to the developer but I believe they are no longer around and there is no forum to check as well. This is my last hope at finding a solution. I hope that someone else has successfully used this add on in P3D v 2.5 and can help me. I am afraid to fiddle around with settings because I just got P3D working the way I want it. thanks