File Explorer Tabs not showing

zrcomputer99, The feature is under testing and is rolled out to some set of Insiders. You can wait for now till it appears to you.

This is mentioned in the official blog on announcement post of build 22621.160:

We are beginning to roll this feature out, so it isn’t available to all Insiders in the Beta Channel just yet as we plan to monitor feedback and see how it lands before pushing it out to everyone.