Step 1: come to the directory you want to protect, create a file index.php which has

and get the home directory from DOCUMENT_ROOT

Step 2: modify .htaccess and add this snippet

Step 3: create .htpasswd

the password is usually MD5

https://shop.alterlinks.com/htpasswd/htpasswd.php

Some errors:

1. Which directory will be locked depends on which .htaccess you modify.
2. You may get Internal Error since your Document_Root is wrong, it should be same as phpinfo();
3. It keeps asking password. You need to use the attached link to get your generated password.