When I open the help menu on my Mac the screen is blank.
Depending on your security settings or version of Safari, the help file might not load properly. If the menu on the left appears, just select a different category and the contents of it will display on the right panel. If no information is displayed at all, copy the address from the address bar on the top and paste it on a different browser (like Google Chrome or Mozilla Firefox). For ChemDraw Professional 16.x the address is: file:///Applications/ChemDraw%20Professional%2016.0.app/Contents/Resources/SpecialPurpose/ChemDraw%20Help/default.htm#CSHID=undefined
For ChemDraw Professional 22.x the address is: file:///Applications/ChemDraw%2022.2.0.app/Contents/Resources/SpecialPurpose/ChemDraw%20Help/default.htm