[fl0id]

The immediate no for scientific collaborations is zotero support being paid only. If it was just one user, sure they could decide to pay. But no way I am convincing others to sign up. (If this is somehow possible without paying while not ‚syncing‘ it’s not obvious)

[flokl]

If the project owner has paid for pro, all collaborators can use the pro features in the project.

Zotero sync is just a .bib file that updates itself regularly, so if you don't want to pay, you have to upload the .bib file or past the new entries manually.