You can't install it separately because the analogue effects are part of Studio One Pro v5 installation. The only need to install them separately is for use in 3rd party applications like Vegas Pro, or Cakewalk by Bandlab via Presonus Hub. As a member of sphere you have access to Studio One Pro v5.2.1 which natively includes the Analogue effects like Redlight Distortion, Rotor etc. Or, if you only use Artist version and bought them separately. But, you mention Sphere which includes a licence for Pro v5. So, there is no need to install them separately.