Thanks for all the responses. I tried doing the process all over from the start and I followed the instructions on the PADT blog. And I had some issues, first when i try to clean up the geometry is space claim, the "use density attributes" check box doesn't come up, also if I ignore that and try to click on the green tick to complete the shelling of the selected geometry, it doesn't work. I don't know exactly why that is happening.
These are minute issues but without resolving them i can't move forward. I am using ANSYS 2019 R1. Also after the lattice optimization doing an FEA validation test is very computational expensive so I thought I could use material designer to get the homogenized mechanical properties of the lattice region and use that in a fully solid body; but trying to copy the geometry from space claim to material designer I get a unit error saying something like material designer works with micro units and the geometry was in standard units- this is despite the fact that the units in space claim when i try to clean it up are showing micrometers and not millimeters.
Any help or suggestions will be appreciated. Attached to this is the archive file