Store today's date as a variable

You need a code similar to this:

// Get the current date

var currentDate = new Date();

// Array of month names

var months = ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'];

// Get day, month, and year

var day = currentDate.getDate();

var monthIndex = currentDate.getMonth();

var year = currentDate.getFullYear();

// Format the date into a single string

var formattedDate = months[monthIndex] + ' ' + day + ', ' + year;

// Set the variable value in Storyline

GetPlayer().SetVar('currentDate', formattedDate);

You will insert this code into a trigger to run JS. 

In Storyline, you need to create a text variable called currentDate and display it on the screen in the desired location.