Correct. You say you used to, but this is the conventional way. The “unique identifier for a paper” is the cite key that you put in your bib file such as “ackoffDataWisdom1989” from the example of FILE 3 in our previous exchange. You probably let Zotero generate cite keys. When you use a cite key in ROAM_REFS for org-cite, you prefix them with an @ as we discussed.
Not conventional if you use bib’s cite key — the granularity of each entry in a bib file does not go down to the page level for written materials (e.g. see Entry types of BibTeX onWikipedia). You usually add page(s) as a “locator” like “[@ackoffDataWisdom1989 pp. 9]”.
Perhaps the diagram I did a while ago might help.
What’s not illustrated in this diagram is ROAM_REFS.
So what’s ROAM_REFS for in this context? It lets you have backlinks. You use it to designate a node as the “canonical node” for the bib entry with using the cite key in the bib file. (Org-roam User Manual).
This old post might help. ROAM_REFS used be ROAM_KEY. The intended use should be the same.