Just to be sure - I see localhost in your domain on the URL - are you attempting for Qlik Sense Cloud Business to connect to a resource on itself? I assume not as your resource is not located on our hosted cloud servers - or is it? You would need to change the localhost domain to the appropriate named of the server you are looking to connect to.
Please clarify and I will attempt to further assist.
I see - thanks for the clarification - Qlik Web Connectors on Qlik Sense Cloud has been implemented differently than on on premise installation. Not all the Web Connector that you see in the on premise installation of the package are available with QSCB - and as you can see in the data connector dialog (available from the create connections button when in the Data Load Editor) - these are the ones that are available (screen shot below). They also have their own GUI implementations so they can grab data in a standard manner similar to other connectors where in the on premise installation in generates script that you paste into the data load editor - this also requires you to run in non standard mode (legacy mode) which is a way to use the older data connection method on your server - which is not supported on QSCB.
What specific connector are you using?
I am assuming this one:
based on the URL you are using - that particular connector is not part of the QSCB web connectors package.
You may be able to get this to work with Web File - however there isn't any security with Web File: