Getting error while Adding external jQuery And extra packages in keycloak customize theme

while adding following file in .ftl file

 <link href="https://cdnjs.cloudflare.com/ajax/libs/intl-tel-input/17.0.12/css/intlTelInput.min.css"        rel="stylesheet">
 <script src="https://cdnjs.cloudflare.com/ajax/libs/intl-tel-input/17.0.12/js/intlTelInput-jquery.min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/intl-tel-input/17.0.12/js/utils.min.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery.mask/1.14.11/jquery.mask.js"</script>

i am getting error

Not quite sure what is going on there, but most of the errors you show relate to files served from localhost:8080,

jquery is not define and the other package css import issue

ive tried another workaround also. i’ve downloaded all the css and js file from above links and maintainer in customized theme folder. still same error.
1.jquery not define (using $ on js file after importing jquery)
2.didnt applying css files to class

if there any other workaround i can follow.