Does the Post Office provide study materials for free?

No. The Post Office used to provide basic study materials in Publication 60A when the Postal Battery Exam 473 was the required exam. As of April 1, 2019, the 473 exam was replaced with four entry-level virtual assessments (474 for Mail Carrier jobs, 475 for Mail Handler jobs, 476 for Mail Processing jobs, and 477 for Customer Service Clerk jobs). The Post Office has not provided study material for the virtual assessments.