Hi,
Under Containers section, there is this part:
If the process works on multiple browser windows (because Browser object is not serializable in case of InvokeWorkflowFile with Isolated option), we recommend calling the GetAttribute activity to get the process ID (PID) of the browser and to use it in the selectors of subsequent AttachBrowser activities, like:
"<html pid='" + browserPid + "' />"
To the best of my knowledge, this will not work with browsers (see #57465 and earlier related) as PID is not currently supported for Browser object selectors (it is for Window type objects though) and also most major browsers can have multiple windows under same PID (Chrome definitely, Firefox either already or soon, Edge I think also, IE not IIRC).
Regards.