ARCADY is started automatically by Autodesk Civil 3D 2020 so there is no need to prepare anything other than to ensure that you have a full copy of ARCADY 8 or above and that you have registered the link.
If you do not have a compatible version of ARCADY installed, Autodesk Civil 3D warns you when you try to enable it.
If you have a compatible version of ARCADY but the ARCADY-Autodesk Civil 3D link is not registered, then ARCADY warns you when it is started.
Once started, the Vehicle Tracking menu within ARCADY allows you to check or configure the link. You should refer to the ARCADY documentation for full details but suffice to say, a green menu indicates that at least one file in ARCADY is controlled by Autodesk Civil 3D.
There are options to change the listener port but you must ensure that both programs are using the same port.