Vertex Coloring Alpha Values for Forcefield Material

How can I vertex color the mesh so that the Forcefield appears half opaque? I have tried vertex painting the mesh in blender and using a remove alpha brush. When I export the mesh it is the same. How can I paint the mesh so it has an alpha value of .5 and then export it with the vertex painting?

I am trying to do what this post says is possible with vertex alphas.
The picture is the Forcefield material in a special mesh with a texture. There is a semi transparent neon part under it.


I’ve been trying to import vertex colors for so long, it doesn’t seem to work, i even searched about the exact add-on they are using (in the images of the announcement post) and i still couldn’t import them, i don’t understand if it’s blenders problem exporting these vertex colors or roblox not interpreting them correctly

You have to export the meshes as fbx

I know objs don’t support it but fbx didn’t seem to work either, I’ve tried multiple times