You have a lot of work to do in SpaceClaim or DesignModeler to convert all the thin-walled solid body parts, such has this box shown below, into mid-surfaces sheet bodies.
All the bracing ribs should be converted to midsurface models.
Only the Top Slab and Bottom Slab should remain as solids.
It's always best to say what version of Ansys you are using. I could tell from opening the solution information that you are using 2019 R3. If you tell me that, then I won't open the file in newer versions. That way, if I make a change, I can pass it back to you in a way that you can open it.