Downpayment Toward Equity Act of 2021 This bill establishes a grant program through the Department of Housing and Urban Development for states and other entities to provide qualifying assistance to certain first-time, first-generation home buyers in purchasing their first homes. Qualifying assistance includes assistance for mortgage down payments, mortgage closing costs, reduction of mortgage interest rates, subsidies for shared equity homes, or for certain preoccupancy modifications to a home to accommodate persons with disabilities. The bill also establishes grant requirements regarding home buyer income, types of housing, homeowner occupancy, types of mortgages, and home buyer counseling.