the library uses WiFiClient class from WiFiNINA, WiFi101 or esp WiFi libraries. use of WiFiClient compiles for all these libraries. to support Client class named EthernetClient class would require changes.
the Ethernet library doesn't support secure connection (a.k.a. SSL). to connect to Cloud over secure connection would require additional (3rd party) library to support secure connection
Thanks @Juraj that is very helpful. Do you know how I could go about finding someone who could write a library for me to do this (willing to pay obviously) as I could really do with this functionality?