“Our server cannot access your shop domain. ” error

Hi I installed your plugin but it is giving this notice “

Our server cannot access your shop domain. Please note you need a working domain (no localhost) that is accessible from the internet and is not password-protected.

Note: Currently we do not support wordpress setup in a sub-directory (eg: example.com/this-is-a-sub-directory/), only root directory is supported, e.g.: yourdomain.com or shop.yourdomain.com

Check your setting, hosting or cloudflare to whitelist the /wp-json/* urls, it is needed for our system to contact your shop.” I contacted to my hosting support they said wp-json is already whitelisted but i still can’t setup this plugin. Can you please help?