Thanks for contacting support. Your DXF file will require manual cleanup. Why? To fill an area, Gerber format requires closed and continuous outlines. I provided our DXF/DWG Conversion rules in a previous support ticket which explains why, and it includes movie tutorial demonstrations. https://www.numericalinnovations.com/pages/dxf-dwg-conversion-secrets-for-gerber-gds-ii-odb-etc
Note: You will also need to delete the Crosses over each circle, as they will only interfere with the boundary fills and do not appear to serve any purpose in Gerber format. Lastly the PCB board outline is made of hundred small segment, when it should be a single outline and preferably on a different layer (named: outline, border, etc.).
Here's tutorial showing how to clean your DXF before converting to Gerber, https://support.numericalinnovations.com/support/discussions/topics/14000003310
Lastly, if you do not wish to clean DXF you can try using SOLID Hatch in any CAD tool. ACE can then convert and fill using the Solid Hatch. However since your design does not have very clean boundaries, even CAD Hatch tools cannot recognize boundaries to make solid, https://numericalsoftware-update.s3.us-east-1.amazonaws.com/tutorials/2023-03-24_12-10-01-hatchfailed.mp4
I wish there was an easy way for you to convert this specific DXF to Filled Gerber without having to perform any editing, but you need to fix your DXF before converting. That's about all the advice I can offer.