Type the author surnames one per line, add the year and the page number if you have one, and pick your style. The correct parenthetical and narrative forms appear side by side with the rule that was applied.
A parenthetical citation puts everything in brackets at the end, such as (Smith & Jones, 2020). A narrative citation puts the authors in the sentence itself and only the rest in brackets, such as Smith and Jones (2020) argued that.
APA uses the first author plus 'et al.' from three authors upward, MLA does the same from three authors, and Chicago author-date uses 'et al.' from four authors while listing two or three in full. The helper applies whichever rule matches the style you pick.
For a direct quotation, yes, in every style. For a paraphrase APA and Chicago make it optional but recommended, while MLA expects a page number whenever the source has them.