PSD importer for 2D rigging

I tried following this tutorial : https://www.youtube.com/watch?v=3Sa-5hi362M

But when I attempt to import my PSD file in unity, I don't have the same options available as the video : I can not see the "mosaic" and "2D rigging" checkboxes. I tried other settings, and I can either have the whole picture as one single sprite, or nothing at all. And of course, both aren't acceptable as the whole point of this is to 2D rig my sprite with it being properly separated into parts (arms, torso, etc)

My guess is the importer changed recently. How can i make this work now?

Note : my sprite is MASSIVE. I am using it to do an "animated painting" like you can see in TCGs like Gwent or Heartstone. Maybe this changes the problem also?

Any help would be really appreciated. I have to animate this painting relatively quickly for commissioned work. Thanks.