Hello @Ryan-Min,
For me, there is no specific CAD model file for the gps mast. You need to use the full CAD model of the drone Starling 2 Max which is downloadable in developer download section. You have to create an account.
Here is a direct link to the most recent model version V3 : D0012-4-V3-C28-M36-T7-K0-Starling2-Max-V3-20260317.step
The last changes to the model are supposed to improve GNSS performance. You can check the doc page EMI Mitigation for GNSS Applications for more information about this topic and their suggestions.