@manni27 There isn’t really much detail to study. Typically (there is not much variation among the programs I have used for this) you type (or copy and paste) a temporary citation in your text or footnote. This will look something like {Smith, 2020, #123@10} – in other words, the author, the date, an ID number, and after the ampersand, the page number (page number is usually optional). BibTex is a little different, but not that much. Some programs, like Bookends, allow text to be prepended or appended to the temporary citation before insertion. If you specify the bibliographic manager in Scrivener’s preferences, all you need to do while writing is to hit Command-Y and you will swap to the bibliographic manager, where you can find your reference, and another keystroke will take you back to your text and insert the temporary citation.
If I know I am going to be inserting references to the same work repeatedly (not uncommon in the work I do) I will copy the temporary citation, and just paste it in when I need it, without switching to Bookends. This can be helped by using a clipboard manager like Copied, which stores previously copied items. If I know a particular reference is going to crop up repeatedly in my work over an extended period of time (e.g. a standard text in my field) I set up a text substitution. So if I want to cite Freud’s Mourning and Melancholia I just type “jjmourning” and the temporary citation {Freud, 2005, #12682} is automatically inserted into the text for me (I use the prefix “jj” because, as far as I know, there are no words in English that begin with “jj”, and “jj” is in the middle of my keyboard). But of course you can set this up how you like. Among other things, a possible advantage of using temporary citations is that they are ordinary text, so you can search for them using normal find. This might be useful if you want to find how many times you have cited a work, or where you have done so.
When you have a final draft, you compile to rtf, and (in my case in Bookends) you scan the rtf file, which automatically replaces the temporary citations and creates the bibliography – usually in a matter of seconds (it did with my 85,000-word doctoral thesis). I find it difficult to imagine anything much simpler.
In days gone by I did use Word’s “Cite While You Write” feature. But only for about thirty minutes. It was dreadful. Every time you inserted a citation it had to create a field, update the whole document, reformat the bibliography (including sorting all the entries), and autosave. For a single-page document it might have been bearable, but I cannot imagine what it would have been like to do a longer piece of work with hundreds of pages and hundreds of references. I believe experiences of this kind are why some of us are highly sceptical of “plug-ins” that are supposed to do various things “magically and without effort” for the user. Often, they do not work very well. Like so many things they hold out great promise and seem very attractive before you use them seriously. Then when you use them, you find out what the disadvantages are. Simple solutions like temporary citations are fairly bullet-proof, and they are also portable and durable. I was able to take texts I had written in 1995 using temporary citations created with Endnote, and scan them with Bookends twenty-five years later. That matters when you are building up a body of research material and you are not sure what the future may bring.