The CSS not working normally means your .htaccess isn’t working… So in this case, it’s your web.config not being set up right and that’s the practical limit of my IIS knowledge :/
Thanks for the insight Ipstenu. Your comment pointed me to search more specifically on web.config file. I found a post which suggested changes to the file (see below) and it’s working perfectly now. Here is a link to the post: http://ww.wp.xz.cn/support/topic/multisite-install?replies=4#post-2198998
Here is what I am using for my web.config:
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<system.webServer>
<rewrite>
<rules>
<rule name="WordPress Rule 1" stopProcessing="true">
<match url="^index\.php$" ignoreCase="false" />
<action type="None" />
</rule>
<rule name="WordPress Rule 2" stopProcessing="true">
<match url="^([_0-9a-zA-Z-]+/)?files/(.+)" ignoreCase="false" />
<action type="Rewrite" url="wp-includes/ms-files.php?file={R:2}" appendQueryString="false" />
</rule>
<rule name="WordPress Rule 3" stopProcessing="true">
<match url="^([_0-9a-zA-Z-]+/)?wp-admin$" ignoreCase="false" />
<action type="Redirect" url="{R:1}wp-admin/" redirectType="Permanent" />
</rule>
<rule name="WordPress Rule 4" stopProcessing="true">
<match url="^" ignoreCase="false" />
<conditions logicalGrouping="MatchAny">
<add input="{REQUEST_FILENAME}" matchType="IsFile" ignoreCase="false" />
<add input="{REQUEST_FILENAME}" matchType="IsDirectory" ignoreCase="false" />
</conditions>
<action type="None" />
</rule>
<rule name="WordPress Rule 5" stopProcessing="true">
<match url="(^[_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*)" ignoreCase="false" />
<action type="Rewrite" url="{R:2}" />
</rule>
<rule name="WordPress Rule 6" stopProcessing="true">
<match url="^([_0-9a-zA-Z-]+/)?(.*\.php)$" ignoreCase="false" />
<action type="Rewrite" url="{R:2}" />
</rule>
<rule name="WordPress Rule 7" stopProcessing="true">
<match url="." ignoreCase="false" />
<action type="Rewrite" url="index.php" />
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>
