As Darren has mentioned your refinements are still very likely incorrect. I’ve copied your project over and am currently meshing but as what I’ve replied before, these are the kind of refinements you want to do. Check the parameters under “Barry’s Mesh”.
EDIT: Looks like the Hex Parametric meshing is giving me some instant errors so I’m correcting it at the moment, get back to you on this! (Fixed by re-uploading geometry as IGES instead of STL)
After you have meshed you can run the simulation. I will set it up for you similar to what I’ve replied before so you can try to run and we can go from there.
That’s what we do ! Hope you don’t get discouraged and keep on trying!
P.S If you require further explanation or are interested in the reasons for why things are done a certain way you can always ask here or check SimScale’s great documentation! It certainly helped me understand what was going on when I first started out not too long ago as well!