The PR card application is generated once your eCOPR document is issued. You don’t have to do anything.
To link it, you just log into your GCKey & there’s a link you can click to “link an existing application to your online account”. Then it just asks for your UCI & some personal details to locate your file. After that my application just came up and was added to my profile & I got an email confirmation.
Was a few weeks back now but it seemed pretty straightforward