A client set up a folder for me to upload files. The problem I'm running into is that DB is counting the files against my account. For example, DB says I've exceeded my capacity limit and I cannot upload anymore files. This is the first time running into this issue. In the past, the uploads to client folders did not count against me.
The only difference is - I believe - that the client invited me to join the folder with an email not associated to my DB account. But when I clicked on the invite, DB opened with my account email.
It sounds like you've joined a shared folder owned by another user.
As you've discovered, shared folders do take up quota on your account. As every member of a shared folder can add and modify the files in the shared folder, the shared folder takes up space in each member's account.
If need be, you can ask the owner to create a file request if you only need to upload files to their account.
If you need any more details, feel free to message back!