This is what the Flux documentation says about exporting Gerber files:
“Gerber files are the industry-standard format for PCB manufacturing. Flux makes it easy to export complete manufacturing file packages for fabrication and assembly.
Quick Export Guide
To export Gerber files and manufacturing data from Flux:
- Click the Flux logo in the top-left corner
- Navigate to Export > Manufacturing Files (Gerbers, etc)
- A ZIP file containing all necessary manufacturing files will be downloaded
What’s Included in the Export
- Gerber RS-274X files for all copper layers (top, bottom, and internal)
- Soldermask layers (top and bottom)
- Silkscreen layers (top and bottom)
- Solderpaste layers (top and bottom)
- NC drill files for holes and vias”