@santhosh
We have checked using your ftp and found
.htaccess file is missing in root of your site. refer this:
https://prnt.sc/tgnv2f
Please
contact your hosting provider for missing .htaccess file.
We are using "
Authorization" key in headers to verify the user refer this :'
https://prnt.sc/tgnub7
As in .htaccess file we add these lines to solve the issue:
SetEnvIf Authorization .+ HTTP_AUTHORIZATION=$0