Exclusions not being added to Bitdefender free (can't find any more product or year details)

Hi all - very new member here, so please be kind: I'm using the free version for the moment, and having issues with adding an exclusion. I use Asus WebStorage for backups and general cloud storage, but I'm unable to either log in to the installed client or download from the website (where I can log in via a browser). Same story with my Zoho account.

At each login, download, or folder access Bitdefender logs a threat and blocks the action.

I've tried adding both folders and domains as exclusions, but Bitdefender in each case says 'could not be added' without explanation.

Is this a known issue, or maybe because I'm using the free version??

Any help very gratefully received. Otherwise something is going to go - and it can't be Asus or Zoho!!