Hard drive full of system data on macOS, how can I change it?

For me, the person I talked to yesterday told me I was on File Provider.
The location is under user/library/CloudStorage/

If this helps..!

Hello again, thank you very much for your help. I have now been able to solve the problem for the time being. The folder, which is not visible in the Finder and was also not accessible, could be found and deleted after several days. In my case it seems to have been a bug from Apple and Dropbox.

Really glad you were able to sort this out, 1839744! 

Thanks for the ticket number, VirageSonore! From the Dropbox location you mention, it looks like you’re on File Provider indeed. 

I’ve located your ticket in our system and left an internal note on your behalf, as well. Please check our team’s latest reply, when you get the chance.

Hi Nancy !
I replied to the ticket this morning, and since then... there's a problem and it says "error loading your ticket" 😞 do you know why ?

1839744 I am really glad you found a solution ! What is that file/folder and where was it ? Did you delete it ?

VirageSonore, how did you try to reply to our team’s email? Directly from your email address or https://www.dropbox.com/support?

I replied on the comment made on our ticket... but now I can't access to the ticket anymore, it says "error loading your ticket"

Just to clarify, are you trying to reply to the ticket directly via your email address, and you receive this error? Can you send me a screenshot of what you see perhaps? 

I'd like to have a visual and guide you from there.

No I went on the link that was sent to me, I could see the whole chat I had, and someone named Daniel I think, responded (looked like this forum here) and I could respond, and I did but now that's what I see : 

Thanks for the screenshot! When logging the ticket, you should’ve inserted an email address, as well. Please check the inbox of that email address, and reply back to our agent from there.