Question.

How to convert an MMD to FBX? https://www.deviantart.com/unluckycandyfox/art/MMD-DL-cute-accessories-783618312 _mmd_dl__cute_accessories_by_unluckycandyfox_dcyjnrc-pre.jpg ^ trying to convert this

Download Cats plugin and install it to blender.
Here's a vid on that : https://youtu.be/UNSatI6zycU

After you follow the tut on installing it, you just import the file as you do to fbx files. Then just hit fix on the cats plugin when you have the box open and it should fix up the pmx file then after that export it to fbx