No. San Marino doesn't ask visitors to fill in an online arrival form (also called an entry form, immigration card or landing card) before they travel. Entered via Italy, where Schengen/EES border checks apply.
Do I still need a visa for San Marino?
An arrival form is not a visa. Whether you need a visa or an electronic travel authorization depends on your nationality, so check San Marino's official immigration website or your own government's travel advice.