When I look at how to publish demo at Wiki and click the ‘public folder’ link and go into Dropbox website, it said I need pro account. Does this mean everyone who published demo have pro account and are there no alternative beside paying?
All Dropbox accounts created before October 4th, 2012, have public folders, free or not. After, it must be paid for.
As @Chwoka said, to use Dropbox, you need either an old account where they let you keep the public folder, or you need to pay.
For a free alternative, I’d recommend webs.com
Never mind, I found solution. You can close this now.