Hello,

1-The message indicates that you may have already installed it. Please make sure you do not have any related files of the plugin elsewhere.

2-Please add these lines into your custom css box:
.blog-article.grid-style .info li:nth-child(1) { display: none;}

3-To disable/not show excerpts at all, add these lines into your custom css box:

.blog-article.grid-style .content .text {
  display: none;
}

To limit the word display, go to file:includes\view\blog\loop-grid.php and find these lines:

<div class="text">
                        <?php   if($post_format == 'video' || $post_format == 'audio')
                                    echo codeless_text_limit(get_the_content(), 20);
                                else
                                    echo get_the_excerpt();    
                        ?>
                    </div>

Replace this these:

 <div class="text">
                        <?php   if($post_format == 'video' || $post_format == 'audio')
                                    echo codeless_text_limit(get_the_content(), 20);
                                else
                                    echo codeless_text_limit(get_the_excerpt(), 10);   
                        ?>
                    </div>

Edit the value of codeless_text_limit(get_the_excerpt(), 10) to your need.

Best regards!