Have you tried the config as provided in the documentation?
https://docs.mendix.com/howto50/deploying-mendix-on-microsoft-windows#45-additional-request-handlers
And is your app on the server actually http://localhost:8080/ ?
<rewrite>
<rules>
<rule name="xas" stopProcessing="true">
<match url="^(xas/)(.*)" />
<action type="Rewrite" url="http://localhost:8080/{R:1}{R:2}" />
</rule>
<rule name="ws" stopProcessing="true">
<match url="^(ws/)(.*)" />
<action type="Rewrite" url="http://localhost:8080/{R:1}{R:2}" />
</rule>
<rule name="ws-doc" stopProcessing="true">
<match url="^(ws-doc/)(.*)" />
<action type="Rewrite" url="http://localhost:8080/{R:1}{R:2}" />
</rule>
<rule name="link" stopProcessing="true">
<match url="^(link/)(.*)" />
<action type="Rewrite" url="http://localhost:8080/{R:1}{R:2}" />
</rule>
<rule name="file" stopProcessing="true">
<match url="^(file)(.*)" />
<action type="Rewrite" url="http://localhost:8080/{R:1}{R:2}" />
</rule>
</rules>
</rewrite>