UC migration from ESA support group to UC + New Style ESA, medical evidence?

I've migrated to UC from cb-ESA and ir-ESA. I've agreed to the UC claimant commitment online but I've now received a letter advising me that my cb-ESA will change to New Style ESA and I need to accept a claimant commitment for that. They will contact me to book an appointment with a work coach at local Jobcentre, either telephone or face-to-face.

The letter says, at the appointment I will be asked to:
explain how my illness or disability affects my ability to work
provide medical evidence
agree to report changes

What do they mean by 'medical evidence'? Is it referring to a fit note? As I was in the Support Group (LCWRA) for ESA before migration I didn't think I was required to provide medical evidence for this process. Is there anything I can do? Who should I contact and how can I explain it? Is it the Jobcentre Plus phone number or can I use the UC online portal? It's confusing to now be under two different systems.

Also, I'm not sure how come I've become eligible for new style ESA. Is the only requirement to have enough NI credits? Or, do you also need to be in the Support Group to qualify?

Hello David,
If we are not on Contribution based esa but on income based esa, are we transferred to New Style Esa same as the contribution esa with UC migration?
Many thanks.
Best wishes

Hi David,

Thank you very much for your reply. That's reassuring to know.

I got the letter about changing to New Style ESA about 9 days ago, but no contact to arrange a work coach appointment yet. Any idea how long it takes them to make contact and will they phone or notify me by letter? Then, how long from contact until the actual appointment; and how much time do they allow to sign the claimant commitment?

Thank you and best wishes.