Help with a pattern

I’m having difficulty with the edging of a shawl. I’ve knitted to the desired length and the next steps are provided below. I cast on 99 stitches and have followed the pattern to 50 inches. I did not cast off as instructed so need to know if I’m to use a separate circular needle to pick up the stitches and use both to knit the edging? Also, am I picking up 3 stitches in every 2 side stitches for the entire long side? I would appreciate any advice on this. Thank you.

"With the circular needles, pick up stitches along each side of the scarf. You have to pick up 3 stitches in every 2 side stitches of the longer sides and 1 stitch in every stitch of the shorter side.Knit 1 row in round. Place one stitch marker
or waste yarn 4 stitches before and after each corner stitch.

Cast on 5 stitches, knit them back towards the body, the last stitch of the edging should be knitted as k2tog with next stitch from the side of the body."

Can you give us a pattern name or a link to the pattern? If it’s a bought pattern, just the name is fine.

It’s the Harathiel Eluchil scarf and I purchased the pattern online. Thank you.

I’m in awe. What a spectacular scarf!

I would cast off the last row as directed. You could leave those sts on the needle however if you wish since you’d be picking up one stitch in each cast off on this short side. You’re going to be knitting the edging perpendicular to the scarf itself.
Pick up the given number of sts around the scarf: 3 in every 2 all along the long sides and one in every stitch on the short side.
You can use the same circular needle for all of the sts. It’s similar to this added edge:

Now I understand it! Sometimes patterns don’t detail enough in the instructions as clearly as we wish. I appreciate your help that will allow me to finish this project. Thank you very much!