According to the README I did not find a way to set the API server properly. There are several API servers as far as I know, such as https://api-cn.faceplusplus.com/facepp/v3/detect and https://api-us.faceplusplus.com/facepp/v3/detect. Face++ may restrict queries to different API server with regard to their locations. In such case, setting API server is useful.