TACACS is Cisco-propietary, and works only with Cisco devices. I don't know if Orion supports Radius. We use Active Directory to log on to the Web Console.
Orion does not support TACACS+ or Radius for its internal authentication. The options you have are individual Orion account, individual Windows domain account, or Windows security groups.
My recommendation would be to create new AD security groups. Add these groups into Orion making sure to set each group up in Orion to have the level of access desired for that group (ir, user level group, admin level group, etc).