I cannot stress this enough: technology is not the hard part.
Do they have outdated software? Yes.
Can you build better software? Yes.
None of that matters if you can't get it into their hands. Procurement is the hard part. Can you empathize with the needs, fears, desires, quirks, and crazy of ten different stakeholders? Pry proprietary API specs from the cold-dead hands of one-off contractors? Educate users who's technological proficiency peaked at SMS to manage a full-featured SaaS product in 2017?
Don't focus on the software. That isn't the hard part. People are the hard part. People are always the hard part.