WordPress error related with the plugin

My WordPress is having issues and sent me an email with this info. Do you know what happens?

INFO:

WordPress versión 5.3.2
Plugin actual: Instant Articles for WP (versión 4.2.0)
PHP versión 7.3.14-1+ubuntu16.04.1+deb.sury.org+1

ERROR DETAILS:

Se ha producido un error del tipo E_ERROR en la línea 247 del archivo /site/wp-content/plugins/fb-instant-articles/vendor/facebook/facebook-instant-articles-sdk-php/src/Facebook/InstantArticles/Transformer/Transformer.php. Mensaje de error: Uncaught Error: Class 'DOMDocument' not found in /site/wp-content/plugins/fb-instant-articles/vendor/facebook/facebook-instant-articles-sdk-php/src/Facebook/InstantArticles/Transformer/Transformer.php:247
Stack trace:
#0 /site/wp-content/plugins/fb-instant-articles/class-instant-articles-post.php(644): Facebook\InstantArticles\Transformer\Transformer->transformString(Object(Facebook\InstantArticles\Elements\Header), 'Jos\xC3\xA9 Bay\xC3\xB3...', 'UTF-8')
#1 /site/wp-content/plugins/fb-instant-articles/class-instant-articles-post.php(873): Instant_Articles_Post->to_instant_article()
#2 /site/wp-content/plugins/fb-instant-articles/class-instant-articles-post.php(950): Instant_Articles_Post->is_empty_after_transformation()
#3 /site/wp-content/plugins/fb-instant-articles/facebook-instant-articles.php(538): Instant_Articles_Post->should_submit_post()
#4 /site/wp-includes/class-wp-hook.p