The more detail you provide in your post the better community members can assist with your question. You didn't indicate which version of the HDP Sandbox you were attempting to use, nor what set of instructions you were following for deploying it using nested virtualization Azure labs.
While we welcome your question, and it will remain visible here in the hope that some other member of the Cloudera Community will answer it, I think it's not at all surprising that you are unable to reach the HDP sandbox's Welcome page after installing the HDP sandbox on Docker while using nested virtualization Azure labs, because the HDP sandbox for Docker was not designed for use with nested virtualization Azure labs.
It may be possible to get that combination working, and indeed some member of the Cloudera Community may have already done so and be willing to share their method, but if you'd like to set up the HDP Sandbox on Docker without using nested virtualization Azure labs, you can read "known good" instructions on how to install it by following the tutorial Deploying Hortonworks Sandbox on Docker, which provides detailed steps to install that combination on Linux, Mac OS X and MS Windows.
Bill Brooks, Community Moderator Was your question answered? Make sure to mark the answer as the accepted solution. If you find a reply useful, say thanks by clicking on the thumbs up button.