Are you running an Intel Mac or Apple Silicon (M1/2/3) Mac?
I'm asking because .ova/.ovf import/export isn't supported with Fusion running on Apple Silicon Macs. As a side note, if you're running on an Apple Silicon Mac that .ova file is probably not going to run. Most .ova files are built with operating systems that require an Intel CPU -- and Fusion doesn't emulate Intel CPUs, making the .ova worthless in that case.