I got to step 8 but when it came to filtering the array, I selected the right outputs, but I don't have key listed under dynamic content and got stuck there. I went through all the steps again to make sure I did things correctly. Any suggestions?
You'll need to use an expression for both keys - they look like dynamic properties in my screenshot, but they only appear that way after saving and reloading the flow.
Locate the image in step 8, right after the sentence with "...might need to zoom in or click..." The two dark rectangles near the bottom contain the expressions I used.