Install Simple Custom CSS and JS Plugin and paste the following JS snippet. You should have jQuery installed to run this script. Your URL must be
https://www.domain.com/page-name/?code=xxxxxxx

// Function to get param from URL string
function getParameterByName(name, url = window.location.href) {
    name = name.replace(/[\[\]]/g, '\\$&');
    var regex = new RegExp('[?&]' + name + '(=([^&#]*)|&|#|$)'),
        results = regex.exec(url);
    if (!results) return null;
    if (!results[2]) return '';
    return decodeURIComponent(results[2].replace(/\+/g, ' '));
} 

// jQuery function to detect code and auto-submit
jQuery(document).ready(function($){
	if ($(".post-password-form")[0]){
	if(localStorage.getItem("submit_time")=='' || localStorage.getItem("submit_time")==null)
		{
			localStorage.setItem("submit_time", Date.now());
		}
	
	var retry_time = parseInt(localStorage.getItem("submit_time"))+60000; // Milliseconds
	var current_time = Date.now();
	var difference_time =  retry_time - current_time;
	
	
var otp = getParameterByName('code'); 
if(otp!='' || otp!=null)
	{
 $("input[name=post_password]").val(otp);
		if(difference_time < 0 || difference_time==60000)
			{
				localStorage.setItem("submit_time", Date.now());
				$(".post-password-form").submit();	
			}
			}
	}
});