the scene contains high-poly and low-poly versions

Who works in the V-Ray version is lower than 3.1. Be careful in the materials in the BRDF section there is a Microfaset GTR (GGX) if your version is older than 3.1 then the BRDF field will be empty. Choose Blinn Phong or Ward – which is preferable to you. ”

“For the Corona render it is recommended to put a version not lower than 1.5 since the glossiness of materials is adjusted to fit PBR.