IIS: not getting an 'Unauthorized' page

I’m pretty sure I’m supposed to be seeing an page telling me I lack authorization. Though I’m just getting a 404.

Any tips?
Hosting in IIS, and I do have some URL rewrite, but nothing that i feel should affect this

        <clear />
        <rule name="HTTPS Redirect" stopProcessing="true">
            <match url="(.*)" />
            <conditions logicalGrouping="MatchAll" trackAllCaptures="false">
                <add input="{HTTPS}" pattern="^OFF$" />
            <action type="Redirect" url="https://{HTTP_HOST}{REQUEST_URI}" appendQueryString="false" />
        <rule name="Remove trailing slash" stopProcessing="true">
            <match url="(.*)/$" />
            <conditions logicalGrouping="MatchAll" trackAllCaptures="false">
                <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
                <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
            <action type="Redirect" url="{R:1}" redirectType="Permanent" />
        <rule name="Root Redirect" stopProcessing="true">
            <match url="^$" />
            <action type="Redirect" url="/Dashboard/" appendQueryString="false" />