How to authenticate user in SharePoint Online using rest api

I have a website on SharePoint Online and a website on SharePoint On-premise. From my On-premise website i want to create a new list on my SharePoint Online site.

To authenticate I used the following codes:

    var soapRequest =
     '<?xml version="1.0" encoding="utf-8"?>
      <soap12:Envelope xmlns:xsi="http://ift.tt/ra1lAU"  
        xmlns:xsd="http://ift.tt/tphNwY"
        xmlns:soap12="http://ift.tt/18hkEkn"> 
      <soap12:Body>  
         <Login xmlns="http://ift.tt/rrg8m0">
            <username>username@email.com</username>
            <password>userpassword</password>
         </Login>
      </soap12:Body>
     </soap12:Envelope>';
 

And then:

    $.ajax({ 
          url: myUrl + "_vti_bin/authentication.asmx?op=Login",
          type: "GET",  
          contentType: "text/xml",  
          dataType: "json", 
          data: soapRequest, 
          success: function (a) {
               console.log(a);
          },
          error: function (a) {
              console.log(a);
          }
    });

As result I get:

XMLHttpRequest cannot load https://myUrl/_vti_bin/authenti…in3!%22%3C/password%3E%3C/Login%3E%3C/soap12:Body%3E%3C/soap12:Envelope%3E. The request was redirected to 'https://myUrl/_layouts/15/error.aspx?ErrorText=Request%20format%20is%20unrecognized%2E', which is disallowed for cross-origin requests that require preflight.

What can I do to avoid the error?

Thank you very much.