APCU extension osticket 1.12.6 php 7.0.0

How to install APCU extension.
Xamp 5.6.32
php 7.0.0
Osticket 1.12.6
MySQL 1.10.28

This does not appear to be an osTicket related question.

Installing the APCU PHP extension depends on that OS that you are running.
I would recommend that you good it.

Also osTicket 1.12 is end of life and no longer supported. I would encourage you to upgrade to a contemporary version.