How to synchronize several different users on the same server?

I have several users of Nextcloud at the same server address.
After creating one user syncronization A with the Windows client I cannot find any way to create other syncronization instances for the other users B, C etc. Whenever I try to add another syncing instance B and enter the address of the server (which is of course always the same) the client is connected with the credentials of A and not connecting to the user B.
How can I solve this problem?

I click on the tray icon, then I get a menu when I open my current account and there I have a way to add another account. I give the server address and then it starts a login-workflow, opening the browser window. There I can choose any user of my instance that I want.

If you are already logged in on your browser, it uses perhaps the already connected account. In this case, Iā€™d logout from your Nextcloud within your browser and then add the other account.