Yes this adhesive strip replacement kit works for the Late 2015 Retina 5K iMac. As mentioned in step 8, the tabs for strip 12 won't line up exactly the same as shown in the guide but it does not matter. It still works and will not interfere with that antenna.
Regarding the screws on the power supply board (step 35), I can confirm these are not T10 screws as shown in the guide. In my Late 2015 Retina 5k model, the screws are T8. Morgan mentioned T9 and depending on your T9 driver, it may just barely fit but can easily slip and strip the screw. A T8 driver goes deeper in and holds the screw properly.