Documentation for zotero indicates unlimited user participation in groups- in practice what are the actual upper reaches of user participation in a public or private group?
If you have 200-400 people adding items to a group, it will need a lot of management or it will be a mess. If this is just mostly read-only access, then I do not see a problem.
The group owner is projecting 200-400 users. Before I give the go ahead to move forward, this is likely not a technical issue?