They should show up under the OctaneLive Accounts....OctaneRender Standalone first, and then OctaneRender for Poser below that. You should have received a confirmation email after your purchased the Poser plugin. They may be a delay generating the username/password. If it is not displaying in a few hours, pls let me know and I'll forward the issue to Otoy.
So to use the "Full integrated plugin", you need the standalone Octane It's is not a fully integrated plugin then its just an interface to the render I'm not going to spend a 99€ (same price as Octane) for that.