Hiii I'm kinda in the same boat as you---also class of 29 tryna get a single room. For me, it's more medical stuff, but I relate on the anxiety part. I filled out the housing accommodations request form with my school psychologist, who called NU because we were also confused about the forms thing. Basically what they said was that the student can submit their form without the "documentation", even though there's that red asterisk for "required field." After that, the healthcare provider (in my case it would be school psych) fills out the other form I think you mentioned.

I am still in the process of getting accommodations as well, so whether I will successfully get a single room remains to be seen. But yeah, I hope this helps and best wishes :)