Install the official free plugin from the advanced custom fields website and remove the SCF version. You won’t need to change any existing code then, and future updates will come from the plugin dev for ACF.
"Just update it!" Until it all goes to shit, and we have to triage the whole mess.
Sorry you are dealing with this, I have spent the better part of the weekend trying to get them to understand this was inevitable.
Devs: "Don't deploy on Fridays" A8C/Matt: "We will deploy on SATURDAYS"