Hi Ujjawal,
So far this looks right. So, as I have understood, "hashedemailID" is the variable that stores the value when the customer signs in.
You need to create a data element for that, so that DTM can pick it's value from the variable from your web page.
Every website implementation has different way to authenticate a user, some uses Windows local storage log in functionality, some uses cookie, some uses hidden HTML element, or JS.
You need to find out where the value is being stored and create a respective data element in DTM.
Thanks,
Varun Kalra