The document discusses the four mandatory documents needed for signup as a seller: cancelled cheque, PAN card, company/warehouse address proof, and GST certificate. It provides details on the requirements and acceptable formats for each document, such as needing a scanned copy of the original PAN card or address proofs being within 3 months. The document emphasizes important points to avoid document rejection, like ensuring names match across documents and not sharing ineligible documents like provisional certificates.