My range too low for the song in Beginner Lesson 8??

I am having a challenging singing along with the high parts of the song in Lesson 8 of the beginner course for deeper voices. How can I adapt to this lesson? 

Hi, Jay! Please try singing on a syllable (like MUH or WUH) that feels relaxed, rather than lyrics. If that doesn't make things easier, consider singing one octave lower for those sections that feel out of reach!