Please use the SAME CamScanner account on your devices to sync your docs.

To find your CamScanner account, please open the CS app on your phone, swipe from left to right to bring out the left sidebar, and then tap your account name on top. Or, please open CS app on your phone--bottom Me--Account. 

After that, you can sign into www.camscanner.com with this account to check out your docs.

How to log out of the website: open www.camscanner.com on PC/Mac--->tap the account name on top right--->log out.