Just wanna check in case you missed it, Have you created arguments for Login-System1.xaml file? It should contain 2 arguments as in your screenshot for System1 URL & Credentials?
Where are you invoking the Login_System1.xaml file? It should be inside ‘InitAllApplications.xaml’. InitAllApplications.xaml should have an argument called ‘in_Config’ which you need to store under your IN arguments of Login-System1.xaml file.
Are you doing this inside the Login file.? Whats the output of that Log message? If you have the proper arguments under the Login_System1.xaml and you are passing the required value as well when invoked then you should be able to retrieve the value of both the arguments from within the login workflow.
Can you attach a screenshot of Arguments tab from within the Login_System1.xaml workflow? Basically you will see that error when you haven’t created IN arguments under Login_System1.xaml file and you still try to create IN Arguments and assign variables while invoking it.