When you open the data, the "Outfit" costume will be registered, so please save it.
From "Back to model selection", select the model you want to wear, and from "Outfit", select the outfit and put it on.
sorry.
I'm using Google Translate.
Are you sure about how to read VRoid data?
After launching VRoid Studio
Models> open> Select the .VRoid you want to open.
If this is set to "YES", others can use this model according to the conditions of use set by its creator. Model data (VRM format) can be provided to other users, who can use it for various VR/AR platforms and other types of 3D content linked with VRoid Hub.
NO
This model's data cannot be downloaded or used for any purpose, and is available only for viewing on VRoid Hub.