[racket] Using 5.3.6 preferences on 5.93

I have Racket 5.3.6 installed and have been using it to learn Racket. 
Yesterday I installed 5.93 as well, but my preference settings from 
5.3.6 didn’t show up in 5.93.

I did some digging in the documentation and found:

http://docs.racket-lang.org/drracket/drracket-files.html#%28part._.Preference_.Files%29

"3.4.3 Preference Files

On Mac OS X, preferences are stored in "org.racket-lang.prefs.rktd" in 
the user’s preferences folder.”

I’m new enough to the Mac that I don’t know what “user’s preferences 
folder” refers to, but was able to use ‘find’ in the shell to locate:

/Users/doug/Library/Preferences/org.racket-lang.prefs.rktd

and my preferences from 5.3.6 are there.

The documentation referenced above also has a note saying:

“The expression (find-system-path 'pref-file) returns the platform- and 
user-specific preference file path.”

But I get the error:

Welcome to DrRacket, version 5.93 [3m].
Language: Beginning Student [custom]; memory limit: 128 MB.
Teachpacks: (lib "guess.rkt" "teachpack" "htdp") and (lib "draw.rkt" 
"teachpack" "htdp").
 > (find-system-path 'pref-file)
find-system-path: this function is not defined
 >

How do I get 5.93 to use my 5.3.6 preferences?

— Doug