Site goes down when auto-translation is enabled

I purchased the paid version of the plugin and enabled deepL automatic translation and the site went down.

Immediately after activation, the auto-translation page showed “
Too many requests. Please try again later.” But when I reloaded the page, it said “The site can no longer be opened.

I received the following error message. Can you please tell me how to improve the situation?

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エラータイプ E_ERROR が translatepress-business/add-ons-pro/deepl/includes/class-deepl-machine-translator.php ファイルの 189 行目で発生しました。

エラーメッセージ: Uncaught Error: Cannot use object of type WP_Error as array in
translatepress-business/add-ons-pro/deepl/includes/class-deepl-machine-translator.php:189
Stack trace:
#0 translatepress-multilingual/includes/class-machine-translator.php(85): TRP_IN_Deepl_Machine_Translator->check_formality()
#1 translatepress-multilingual/includes/class-plugin-notices.php(453): TRP_Machine_Translator->check_languages_availability(Array)
#2 public_html/wp-includes/class-wp-hook.php(324): TRP_Trigger_Plugin_Notifications->add_plugin_notifications(”)
#3 public_html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#4 public_html/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#5 public_html/wp-admin/admin.php(175): do_action(‘admin_init’)
#6 {main}
 thrown