Data_unity3d.zip -

Open Unity Hub , click Add (or "Open"), and select the folder you just extracted.

Standard zip programs cannot see inside a .unity3d file. You need specialized tools: Reverse Engineering Unity.3D Files - DeviantArt data_unity3d.zip

If you downloaded this file from a source like GitHub or received it from another developer, it is likely a full Unity project compressed into a ZIP to save space. Open Unity Hub , click Add (or "Open"),

Unzip the folder to a dedicated directory on your drive. Open Unity Hub