yes, the rendom passwrd will add a binding to the bindings panel, you now need to use the Set Session Value server behavior from cookies toolkit to store the random password in a session variable.
Make sure you have cookies toolkit installed.
Then go to the server behaviors panel, click the plus button and select WA Cookies -> Set Session value.
Set the trigger to Any Form Post. Set the name to "randomConfirm" click the plus button next to value and select the Random Password option from the bindings panel.
In t he insert record behavior, you can set the new randomString column to use the randomConfirm session variable as it's value.