To ensure that you haven't missed the latest updates for AutoCAD Plant 3D 2018 and 2019, I'm just posting this blog post. You can download as usual either via Autodesk Desktop App or via Autodesk Account. Your login will be required therefore. Click in Autodesk Account to "Product Updates" on the left frame. Use STRG+F to find the updates quickly..
These are the updates:
AND: Since late September the Object Enabler for Plant 3D 2019 is published and you can download it from here.