Advanced Editing Lesson 8 Fusion

Hello there. I am training for the certification of advanced editing. I'm on the Fusion lesson. So far so good! I'm on the Keying and Compositing section. Page 270. I have successfully made my Backplate and bluescreen nodes, the Delta Keyer node, I've done my color swatch and alpha work correctly. Done the low threshold and high threshold correctly. Clean foreground is good. I've even successfully created the garbage matte. Now I'm on page 275. It says "Hold the Option (macOS) or Alt (Windows) key and drag the polygon output to the delta keyer node." "You will see a drop-down menu prompting you to indicate the input you would like to use. Select GarbageMatte". I have done this but I am not getting the image of the sync character in front of the back drop/ the backplate image. I understand this lesson is from a Davinci resolve 15 PDF. and I'm using Davinci Resolve 17. I've tried to change my nodes around but I know that isn't the answer. If anyone knows what I did wrong please tell me. I don't want to move onto "Compositing Layers using Color Correction" when the layers aren't even there to do the next exercise. Thank you in advance!