Yes this is correct! The yoke is lined but what you do is treat the lining as the underside of the shirt. So, as per the instructions, you pin the undercollar to the shirt with the right side against the outer yoke piece part of the shirt. You pin all the way around and then carefully sew it, being careful not to create little bubbles and puckers in the shirt particularly. Just go slow and smooth out the layers as it approaches the needle amd you shouldn’t have a problem.
I have made this shirt many times for my son who is now out of the size range and I have also made a couple for my toddler daughter. I find that the more you sew a pattern the better and faster you get at sewing it.
When it comes to attaching the upper collar and closing up the raw edges, I think the instructions say to top stitch. If you feel better stitching it down by hand and then topstitching, no one is going to hold this against you. I think that when you are new to a pattern and particularly new to sewing, if you take the long way round while you are learning the technique, you tend to get a better result.
But at the end of the day, trust Liesl’s instructions. She knows what she’s talking about and she will guide you through it well – and of course ask more questions here too if should get stuck again.
I hope this is helpful and not even more confusing. Please let us know how you get on.