plugins not working in custom theme

Your theme does not contain a main post loop, so there is no place for the plugin to do its work

if ( have_posts() ) {
    while ( have_posts() ) {
        the_post(); 
        //
        // Post Content here
        //
        the_content();
    } // end while
} // end if

https://codex.wordpress.org/The_Loop

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)