JSFiddle - React, Tailwind, and code Playground

HTML

강좌수 <input type="text" name="wr_1">
<br>
강좌 <input type="checkbox" name="wr_2[]" value="a">강좌1
<input type="checkbox" name="wr_2[]" value="b">강좌2
<input type="checkbox" name="wr_2[]" value="c">강좌3
<input type="checkbox" name="wr_2[]" value="d">강좌4

JavaScript

$(function() {
  $('input[name^="wr_2"]').on('change', function() {
      var limit = parseInt($('input[name="wr_1"]').val());      
  		var cnt = $('input[name^="wr_2"]:checked').length;
      if (cnt > limit) {
        alert('강좌수만큼 신청이 가능합니다.');
        $(this).prop('checked', false);
      }
  });

});