Can’t place HTML into Tab

Hello, does this plugin support HTMLand other simple things, like Javascript, being placed in them?

I am trying to add some simple html coding to add a form within the tab but the plugin manager page keeps spitting out unserialized errors. Here is my code and the error:

<script src="https://code.jquery.com/jquery-3.3.1.min.js" integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8=" crossorigin="anonymous"></script>
<script type="text/javascript">
	 $(function(){
		var errMsg;
		
		$('#NewUsrFrm').on('submit', function(event){
                       alert("test");
			event.preventDefault();
			
			var dataStr = $("#NewUsrFrm").serialize()
                        alert(dataStr);
			
			$.ajax({
				url: "/grant/php/addUser.php",
				type: "post",
				data: dataStr,
				dataType: "json",
				success: function(json){
				    onUserAdded(json);
				},
				error: function(request, txStatus, errThrown){
					alert("Error thrown on request.\nError: " + errThrown +"\nStatus: " + txStatus + "\nRequest: " + JSON.stringify(request));
				}
			});
		});
	 });
	 
	 function onUserAdded(json) {
	 	var rtnData = JSON.stringify(json);
	 	
	 	//rtnData = replaceAll('{', '', replaceAll('}','', replaceAll('"','', replaceAll('\\','',rtnData))));
	 	
	 	if (json['Status'] == "Error"){
	 		var eMsgLbl = document.getElementById("errMsg");
	 		
	 		eMsgLbl.innerHTML = json['Message'];
	 	} else{
	 		alert("The user was added successfully.");
	 	}
	 	
	 }
	 
	 function replaceAll(find, replace, str) {
		while( str.indexOf(find) > -1) {
			str = str.replace(find, replace);
		}

		return str;
	}
</script>

<label ID="errMsg" style="color: red; font-size:14px; font-weight:bold;"></label><br/>
	<label for="NewUsrFrm">New User Form:</label>
	<form ID="NewUsrFrm" method="post" action="/grant/php/addUser.php">
		<fieldset>
		    <legend>User Information</legend>
		    <label for="UsrFName">First Name:&nbsp;</label><input type="text" name="UsrFName"/><br/>
		    <label for="UsrLName">Last Name:&nbsp;</label><input type="text" name="UsrLName"/><br/>
		    <label for="UsrAge">Age:&nbsp;</label><input type="number" min="1" name="UsrAge" Value="1"/><br/>
		</fieldset><br/>

		<fieldset>
		    <legend>Login Information</legend>
		    <label for="UsrName">Username:&nbsp;</label><input type="text" name="UsrName"/><br/>
		    <label for="UsrPass">Password:&nbsp;</label><input type="password" name="UsrPass"/><br/>
		    <label for="UsrGrp">Group:&nbsp;</label><input type="number" name="UsrGrp"/><br/>
		    <label for="UsrType">Type:&nbsp;</label>
		    <select name="UsrType">
		        <option value="0">Student</option>
		        <option value="1">Parent</option>
		        <option value="2">Administrator</option>
		    </select>
		</fieldset><br/>

		<!--<button type="submit" ID="frmBtnSub">Create User</button>--!>
	</form>

Notice: unserialize(): Error at offset 2782 of 2782 bytes in /var/www/html/wp-content/plugins/tabs-responsive/ink/admin/add-tabs.php on line 55

Warning: Invalid argument supplied for foreach() in /var/www/html/wp-content/plugins/tabs-responsive/ink/admin/add-tabs.php on line 61