model not slicing wall fill issues

[Dazza1390]

hi guys
new to the 3d printing scene and I've bought my self a second hand Anycubic mega zero v1 cheap. now the issue I'm having is I've drawn up an enclosure for a PCB, it looks fine but when i try to slice it in Ultimaker Cura its zero material and zero time to build. i drew the item in Sketchup 2016 then exported it to an .stl file didn't work then i tried to import it into fusion 360 to see if it was a fill or a conversion from a mesh to a solid but that didn't work as well. I'm obviously missing a step some where but not sure where
also if anyone has any suggestions on what a good 3d modeling program is let me know, wasn't a fan of the controls in fusion 360 and Sketchup is a bit basic so maybe something between Sketchup and fusion
the files attached are first exports that i did but seems to have an issue with the infills