Post indexing issue

I trust this message finds you in good health. I am reaching out to request your assistance regarding a perplexing matter I’ve encountered. Recently, I undertook the task of implementing a Google Instant Indexing plugin for my website, https://dddcodigo.com.br/. Regrettably, every attempt to submit a URL resulted in an error message indicating an undefined submission. Despite diligently adhering to the guidelines laid out at https://rankmath.com/wordpress/plugin/instant-indexing/, I find myself unable to resolve this issue independently. Your expert guidance and support in overcoming this challenge would be immensely appreciated. Thank you for generously offering your time and consideration.