Clients rarely ask what file they are getting. They ask whether they can have it. On SnapStaq the first question has one answer — every download is the original file you uploaded, at full resolution — so the setup is about the second.
Single photos, the whole stack, or both
Turn on single-photo downloads when clients will pick and share a few at a time. Turn on full stack download when they should have everything — SnapStaq builds the ZIP and emails them the link. Both can be on. Many photographers leave singles on and open the stack once the balance is paid.
Limit downloads to certain sets
Downloads can be restricted to specific sets. Keep proofs and watermarked sets view-only, and open downloads on the final set when it is ready. The client sees one gallery; the download button only appears where you allow it.
Add a PIN when it matters
A download PIN keeps a shared link from becoming a free-for-all. Send the PIN separately from the gallery link.
Say it once, up front
Whatever you choose, put it in the delivery message: what can be downloaded, from which sets, and whether a PIN is needed. One sentence there saves a week of "can I download these?" replies.