Thank you in advance for your comments.
I am starting afresh with Dropbox (2T plan).
Case 1. If i have a pdf file on my desktop (MB Pro 2015 OS 11.4). In the web app, if i upload that pdf, then a copy is saved to the folder i was in on the web app. The pdf remains on my local desktop. If i then delete the pdf from the desktop, the pdf stays in the online folder. Is this the desired behavior?
Case 2. I have a Mac Photos library with 10k photos. If i upload the library (located in User/Home/Pictures) then a copy is made on Dropbox's servers. Questions:
a. can i delete the photos from my local library as they will be accessible in the app?
b. I have done this in the past and wound up with multiple photo libraries and very complex folder structures year, month, then long alphanumeric strings for even more subsidiary folders. Is this what is supposed to happen.
c. If i keep the 10k photos on my local Photos app, then if i make changes to the photos and/or delete some, will these changes be reflected in the photos i have on the Dropbox server in the cloud?
d. Do i use selective sync to keep a local copy of the photos? If i do then will the Photos app in MacOS be able to read the local copy.
I think i do not understand syncing and especially the way Dbx handles photo libraries?
I have had dropbox for about ten years and I think i know less than i do when it was only a simple folder in the file structure which was synced to a location in the cloud.
Thanks again.