i think Srujana means how to download the metadata from a vendor (aka Service Provider) and use that metadata.xml file FROM the vendor (aka Service Provider) to create a custom app in Okta for SSO to that vendor (aka Service Provider). I'm looking to do this myself so any help that can be provided would be much appreciated.
There's no XML import functionality. What you'll need to do is open the XML and read through it. The metadata should contain the apps EntityID as well as the Post Back URL, and any other settings that the app requires will be set within the data (just match the content to the options in the saml 2.0 template, and anything not explicitly referenced can retain default settings).