Data files on public servers access

Hello! I use public Sage servers from time to time and I have a question about their work. For example, let's imagine I created a sheet which got a number 3. The corresponding folder with the same name is created on the server's hard disk. Then all what I do on that sheet is stored in that folder, right? - If I want to store some data into a file or to create a text file with some table in it to use it further with other software, those files are also stored in the folder "3", right? If so, then can these files be accessed to only from this sheet or from another my sheets too? - Who is the owner of such files? As far as I understand, when I open any one of my sheets, a new user is logged into a system and all the files created by this user during this session belong to this user. - Can other users access my files if they get the same username under which I had saved those files?