Cannot instantiate TwoCaptcha object in .Net 6

Question

I am trying to integrate 2Captcha service in my .Net6 Application.

I have installed this nuget package: https://www.nuget.org/packages/2captcha-csharp/

Following their official documentation: https://github.com/2captcha/2captcha-csharp

I added the namespace: using TwoCaptcha.Captcha;

But I am not able to instantiate the object:

TwoCaptcha solver = new TwoCaptcha('YOUR_API_KEY');
reCAPTCHA captcha = new reCAPTCHA();

Getting error here.

How can I resolve this?