Hello,
The ATECC608A driver was a proof-of-concept for the first draft version of the secure element driver interface. The driver interface has changed considerably since this first draft, and we have not ported the driver to the current interface.
The driver is for Mbed TLS running on Mbed OS, and requires the chip support package provided by the hardware manufacturer (https://github.com/MicrochipTech/cryptoauthlib). There are quick start instructions at https://github.com/ARMmbed/mbed-os-example-atecc608a . I think the driver still works with the latest version of Mbed OS, but it's maintained by a different team at Arm and I haven't been following it lately.
The Mbed TLS team intends to create and maintain a new example driver, for the current driver interface. It will likely be available by the end of Q1 next year. We don't know yet whether it will be for the same secure element. (If someone else intends to make an ATECC driver, please let us know so we don't duplicate effort!)
Please note that we never intended this example driver for production, so it may have functionality gaps, an inability to suppress debug output, etc. However, to the best of my knowledge, it accomplishes its basic purpose and is secure (as much as unmaintained software can be secure).
Best regards,