Hello,
Unfortunately the Product custom fields isn't possible with the Starter version (free), as you can see in our
Compare page
.
Now, the fact that your specification tab is display, while there is nothing to display is strange, can you provide more elements in order to allow us to better understand the situation, can you process a test with a default template (Cassiopeia for J4 or ProtoStar for j3) and make your returns if that change something or not
=> And please, be specific on your returns.
Awaiting your returns.
Regards