You have a WordPress.com blog, it’s entirely separate from www.remarpro.com.
They don’t allow plugins on WordPress.com for security reasons. Plugins are a feature only available to self-hosted www.remarpro.com blogs. You can find out more about that here: https://support.wordpress.com/plugins/
They do have several built-in features that were inspired by many popular plugins. You might find what you want by searching for it at https://en.support.wordpress.com/
For more information on the differences between WordPress.com and www.remarpro.com, please see: https://support.wordpress.com/com-vs-org/
Also, for help with your WordPress.com blog, contact https://en.support.wordpress.com/contact/
