I try to secure a specific folder and all files and subfolders with this location block:

location ^~ /folder1/admin {
auth_basic "Login";
auth_basic_user_file /var/www/domain.tld/www/folder1/admin/.htpasswd;
}

With this code nginx offers always to download the php files.

With this code everything works as expected except that files and subfolders are not secured:

location /folder1/admin {
auth_basic "Login";
auth_basic_user_file /var/www/domain.tld/www/folder1/admin/.htpasswd;
}

Why is that and how can I fix the problem from the first block?

Thanks.