Private share not working in Windows

sorry getting very tired and frustrated

Set up 3 Cloud users, all with different usernames and passwords

set up 4 private shares, 1 for each user and 1 shared by 2 users

copied some files to public share

then when try to copy files from anywhere to  one of the private shares, get windows message about entering passwrods and user names.

however no usernames or passwords are accepted.

research this forum and Windows and it seems Windows only allows network connection to have the same user name and password

tried advice to disconnect network drive using windows command but then have to reboot which isn’t going to be workable in daily use as any one user will be needing to access private and public shares, and through their own cloud usernames.

Any ideas?