I am leasing a space in a building for a business purpose. The Lease states that I (the Tenant) am responsible for compliance with TAS / ADA. What should I do?

Make sure the construction documents are submitted for review and that the construction is inspected. If the Landlord agrees, have the Owner assign you as the Owner Agent Designee. You will be able to manage the process to ensure compliance. If the Owner will not designate you, find out who will acting on behalf of the Owner.