Staging issue

Staging related ask:
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Say my working production website is here: https://developer.polarbd.com/bn/ And in this website we’re using polylang plugin for 2 languages.
Now I’ve cloned/staging the website with wp-staging plugin. Now my new URL is: https://developer.polarbd.com/polar-old/bn/ But when I visit here: https://developer.polarbd.com/polar-old/bn/ It shows 404.
It should show us the home page normally. What can we do now to see staging home page here https://developer.polarbd.com/polar-old/bn/?
Thanks!