Ferr Vertex Paint and Toz Vertex Paint

Hi everyone,
I just purchased this two assets on the store, but I have a problem with toggling the brush inside the editor to paint over my mesh.

I have everything set on the mesh (collider etc), i tried with the examples meshes and scenes but I just can't switch to the brush. I get the regular cursor wich selects the mesh.

I can apply vertex colors with the bucket fill but can't paint.

Is there something I need to do to be able to paint on the mesh?
I use version latest 2019.4.f1

Thanks!