Hi There,
Welcome to Adobe Forums.
We can only get the name of the user on a slide by assigning a variable to any text entry box and user has to type the name because Captivate need an input to take the value.
Example:
1) You can create a variable name studentname with a value of 1.
2) Add a text entry box on first slide and then in Properties go to General (tab) > Variable and assign the variable studentname to the text entry box.
3) Second slide add a text box and type $$studentname$$ (which will take the value of text entry box automatically).
4) Publish or preview the project and you will find that the name typed in text entry box will appear in the text box of second slide.
I hope this helps.
Thanks
Vikas