Is octopus smart meter free?

I've come across the term "octopus smart meter" and I'm wondering if it's a free service or if there's a cost involved. Can you clarify if octopus smart meters are available for free, or do customers have to pay for installation or usage? Additionally, are there any benefits to having an octopus smart meter that might justify the potential cost? I'm particularly interested in understanding the financial implications and if it's a worthwhile investment for homeowners.