Welcome to the site!
New users are just as welcome as anyone else. Plenty of new users have made incredible contributions to this site with amazing answers, and our community thrives on bringing in new users to answer questions.
That question you linked has six deleted answer that you can not see right now, and the standard across stack-exchange sites is to protect questions automatically once there are three answers deleted. This is because PPCG is powered by the software for a Q&A site, and if 3 or more answers are deleted on a question, (not a challenge) it's probably attracting spam/non-answers/arguments. Protecting questions is a line of defense against this.
But PPCG is not a Q&A site, so this standard doesn't work as well. In fact, that's even why I wrote this meta post asking for advice for what to do to protected questions. I have already unprotected that question once before. Now that Dennis has unprotected the question, you should be able to post your answer as usual.