Thanks for advice, but I would like to use it on our "start" page. It already has other blocks.
As a workaround I tried to "Create a new block" on the admin pages there the plugin actually is visible but instead I get this error message when I try to create the block:
"OutOfRangeException: (0)
#0 /var/www/html/x274934/applications/cms/sources/Blocks/Block.php(1003): IPS\_Widget::load(Object(IPS\Plugin), 'TDBPosts', 565620735, Array, NULL, NULL)
#1 /var/www/html/x274934/applications/cms/modules/front/pages/builder.php(112): IPS\cms\Blocks\_Block->widget()
#2 /var/www/html/x274934/system/Dispatcher/Controller.php(85): IPS\cms\modules\front\pages\_builder->previewBlock()
#3 /var/www/html/x274934/applications/core/modules/front/system/widgets.php(38): IPS\Dispatcher\_Controller->execute()
#4 /var/www/html/x274934/system/Dispatcher/Dispatcher.php(146): IPS\core\modules\front\system\_widgets->execute()
#5 /var/www/html/x274934/index.php(13): IPS\_Dispatcher->run()
#6 {main}"