In English "the" is not required before ordinal numbers. For example:
"A 1st place winner is allowed to race in the next heat."
In fact, often no articles are present before noun phrases. This is referred to as "zero articles". I have listed several links describing zero articles at the end of this post.
From the Wikipedia article (listed below)
The zero article is also used in instructions and manuals. In such cases, the references in the text are all definite, and thus no distinction between definite and indefinite has to be made.
I believe this is relevant to the question asked as the original question sounds like instructions on how to use 2nd and 4th cases.
https://en.wikipedia.org/wiki/Zero-marking_in_English#Zero_article
https://www.thoughtco.com/zero-article-grammar-1692619
https://www.englishclub.com/grammar/determiners-zero-article.htm