Unsure if this is true.
Automatic login from web URL to IWP details please
You can't store the account and login details in the URL. But you can make one specific account function as an auto-entered account + password so that a URL that simply goes straight to the database will open it without a login dialog.
Admittedly they don't make it transparently easy.
a) First decide which privilege set the automatically logged-on people or person should have. Read-only, Data Entry Only, or something custom. Whatever priv set you decide to go with, enable Instant Web Publishing only for that privilege set, no others.
b) Enable one and only one account for that privilege set.
c) Under File menu ——> File Options, enable automatic logon for that account. It can be the Guest account, by the way, as long as the Guest account is the only account using the IWP-enabled privilege set.