Can't Backup an external drive

Issue details: 1st, let me say that the support offerings are dismal, especially when paying for a higher-level subscription. I, as a support consultant for dozens of clients, assist them with their issues so they don't need to go through the laborious, time-consuming, stupid, wasteful, "chat" or other BS functions to get support, and normally, for well over 30 years, I've been pretty much successful. I am somewhat of an advocate for my clients. However, the wasted effort as of late to achieve a simple, easy function of uploading, syncing, and populating the Dropbox "cloud" with data from an external 4TB drive (2 TB populated) has been problematic, time-consuming, and unsuccessful. Answers provided via Google search results, AI, and even your community forum do not even in the slightest help at all. I was told to copy/paste the community forum discussion to generate a support ticket. To summarize, before I do so, a 4TB external NTFS disk on Windows will not upload to Dropbox in the cloud, repeat gets stuck, never gets past 3 or 4 files, says fils in use (they are not), and if chosen to use the Web interface to upload multiple folders, I cannot, I can only "babysit" one folder at a time, wait, do another, and then the Dropbox cloud gets populated, so does the local disk, which is space limited, so there is no "easy solution to get files to be available from an external device to the Dropbox cloud for "safe keeping", as what is the intended purpose of a cloud-based repository. My client, xxxxxxxx, account xxxxx@xxxxxxx.com, with a 'Professional' account, cannot get her files on the cloud without 1 by by one folder upload (super overwhelming, time-consuming) and filling up her hard disk. So, how is it done, why is it so difficult, and if this product is a mature, well-working tool, why is it that I have to go to such lengths to even have a simple communication with the provider of this software (you/Dropbox), without being told that if I want a 'higher level' support, I'd need to buy a higher level subscription to have telephone support? (And even so, the support could potentially suck, as I've found out in the 30+ years of support that the support persons hired sometimes don't have a clue and we as the consumers report these types of problems as if we were beta testers.