[Plugin: WooCommerce GoPay Payment Gateway] Porting to Classipress?

Hi everyone!
I’m wondering if anyone could help me port a Woocommerce payment gateway to Classipress.
Woo plugin here https://www.ads-software.com/plugins/woocommerce-gopay-payment-gateway/
It seems pretty straightforward, I read through the tutorial here https://www.appthemes.com/blog/developer-payment-gateways/ since the way they’re coded is similat, but I can’t seem to get the functions right and the plugin won’t install.

I tried contacting the plugin author, but haven’t recieved a reply.

Any help is appreciated! Thanks!