Hello @Sohil0,
I had a that problem some time ago with another website. Their number analysis incorrectly decided, for some reason, that my number was not a mobile phone number and wouldn't send the text to it.
You should contact Airbnb support to see if they can send the confirmation text manually or use some other verification process.
They can be contacted in many ways as described in the article below.
This article is one of many in the "Community guidelines" post which you can see if you click on the "Get support" link on the main page of this community help forum.
Contact-Airbnb-A-Community-Help-Guide
Steve.