This is a journal article that the client wants published in  real journal, so the quality needs to be high. The client has done the structure, so your job is simply to fill in the structure with the relevant content. You are to be especially detailed on the Methodology section. It’s a systematic literature review so you are to approach it as a proper SLR. Attached are some sample SLR articles.

Since this article is to be published in a journal, only use papers from well esteemed and top tier journals that have been published over the last 10 years.

Also, the client had tried to write their own article but it was rejected (see attached). Please check to see the reviewer’s comments so that you can know what to do and avoid in your own version