Forms Authentication on Folder.

I have a folder in my asp.net application that hosts an .ics file. This calendar file will be accessed in different ways by clients, one of the ways is adding the calendar via outlook. I need this folder/file to be protected so only authorized users can access it.
I added the folder that contains the ics file to my web.config like so:
<authentication mode="Forms">
 <forms protection="All" loginUrl="/login.aspx"></forms>
</authentication>
<configuration>
...
  <location path="Calendars">
    <system.web>
      <authorization>
        <deny users="?" />
        <allow roles="Admin” />
        <deny users="*" />
      </authorization>
    & ...