How to find the folder size on the Dropbox website

My drop box is apparently too large, and I think it's because I have many shared folders with other organizations (I'm a consultant, so these folders generally belong to the organization I'm contracted with).  I need to know which folders are the biggest so I can figure out how to fix the size issue, for example by asking to be dis-included for folders related to projects I'm no longer involved with. But the instructions I've googled for how to find the size of each folder have been USELESS. I'm trying to do this via the web interface.

 

• I do NOT have a "size column". Don't ask me to click that unless you can first instruct me HOW TO MAKE IT APPEAR.
• Alternate instructions say to simply hover my cursor over a column header to find "size" that way. But simply hovering over a column header does NOTHING, meaning nothing shows up, no options, just absolutely NOTHING AT ALL. I cannot select "size" this way because there is NOTHING to be selected AT ALL.
• If I left-click on a column header, it simply re-arranges the files, still without showing me any options to select from.
• If I right-click on a header, it shows me the following options I can select, NONE of which include "size":

Multi-file organize
Set naming convention
Show deleted files
Request files
Rewind this folder

 

Please advise.