Elsevier's confusing guide for authors I am trying to submit a manuscript to an Elsevier journal Renewable and Sustainable Energy Reviews (RSER) and found the author guidelines most confusing. For example, under author guidelines, it is said that

Use of word processing software


It is important that the file be saved in the native format of the
word processor used. The text should be in single-column format. Keep
the layout of the text as simple as possible. Most formatting codes
will be removed and replaced on processing the article. In particular,
do not use the word processor's options to justify text or to
hyphenate words.

Then it recommends

to use the latest Elsevier article class to prepare your manuscript
and BibTeX to generate your bibliography.

Now, there are two classes and templates available for Latex: cas-dc and cas-sc, one for the double column and one for the single column. Now I am confused,
(a) Which template to use for the submission? Single column cas-sc or double column cas-dc? The author instructions or the user guide for the templates does not guide when to use which template.
(b) The aforementioned instructions are for the source file? Latex source file is already in the single column format.
(c) What should be the layout of the output PDF? Single column or double column? The journal publishes article in the double column format!
(d) Should the PDF files have justified text or ragged right? Latex templates provided by Elsevier produce PDF files with justified text.
I will be thankful if someone can help me out with this. The confusing author guidelines can be found here.
Different fields have different conventions. I am a mathematician, and my advice reflects what I know about publishing conventions in that field. So please take this advice with a grain of salt.
This said: Echoing the comments of m123, sleepy, and Lewian, I would advise you to ignore Elsevier's guidelines entirely. Submit your document in any format which looks attractive, is normal for your field, and is convenient for you to prepare.
You can worry about their guidelines once your paper is accepted, and maybe not even then. My own opinion is that if Elsevier charges $4,034.00 for an annual subscription to this journal, then perhaps they can afford to employ staff to do their own formatting work.