Hi nithys ,

If you want to get the Username of the one that has logged in, do the following 

If you have generalized the Login Entity with Administration.Account then create the microflow as follows,

And call this microflow wherever you want to call the Username using data view and set data source as Microflow and call the above microflow .

And call the FullName attribute from the Administration.Account entity as above. You will get the username of the one that has logged in.

Hope this will help you.