Why is my hair showing up right in blender but not s4studio?

hi! You don't copy the dropbox link that is on the address bar, you click "share" and copy the link that the page gives you. If not, no one else can access it.

For the issue, please check that the cut numbers match the original EA mesh.

It doesn't matter if it is an EA mesh, a custom mesh, a mesh from scratch, a conversion. The NUMBER of groups with its CUT NUMBERS MUST match the original mesh that is present on the package you're working with for the mesh to import correctly.

Your blend has almost 30 groups with the same cut number. The program will import only 1. Group all those part together and see the original blend to guide you. Read the tutorial i linked you.

You'll surely have transparency issues afterwards, this is the only way i can help you with that. I know nothing else.

This is the issue inabadromance told you before. You can follow the tutorial she linked to attempt to solve it. I know nothing about this neither but you can get the idea in the tutorial.