Best way to market free proptech while competitors are pay per desk.

What is the best way to market a proptech company that is free? We are creating a slack app to manage desk bookings, contact tracing, capacity management, health surveys, team schedule, and usage analytics. Right now, the top competitor is a pay per desk system. We are trying to bootstrap it by cold emailing companies that have signed new leases. Any advice would be greatly appreciated on how to get a company that uses Slack to adopt a free technology to ease the return to office process.