Create: Error saving layers because of permissions

Error saving layers because of permissions
Keeps coming up when trying to save file?

2023-05-22 16:37:05 [Error] [omni.usd] ERROR! Failed to save layer omniverse://localhost/Projects/Ballina-St-project/Ballina_St_-_Apartment.usdz due to permission issue.

Looks like a .usdz file type issue!!
Why are there letter extension like a and z on .usd files??