Compilation error: 'WebsocketsClient' does not name a type

I'm trying to define a WebSokcets client with this : #include <WebSockets2_Generic.h>
but got this error and don't know how to fix it i tried a lot of librairies and got the same error.
I'm on R4 arduino uno WIFI.

Any helps is appreciated.

Please post a complete sketch that illustrates the problem and the full error message, using code tags for both when you post them