It looks like you are using IISExpress in your solution.
You can configure your IIS to point to your Solution. To do this, you need to configure a binding for localhost for your website.
To achieve this, you need to open IIS and create a new site via "Add Website". You can choose the Site name freely. The physical path needs to point to your /CMS directory of your solution. As hostname configure localhost.
Otherwise you could do this kind of in your Solution. Right click your CMSApp Project and select "Properties". Navigate to "Web" and switch the dropdown under Servers to local IIS. Now edit the URL to "http://localhost" and click "Create Virtual Directory". Save the Project, build again and should work too.