Problem with AWS IoT Device Certificate on Unity

Hi, I'm trying to integrate AWS IoT Core to my Unity project. However, i'm currently having problem with device certificate. I'm using System.Security.Cryptography.X509Certificates library and below is my function. I used Openssl to covert the device certificate from pem to pfx file with the private key. When i run the program, it return this error. A post on stackoverflow (https://stackoverflow.com/questions/74884020/m2mqtt-argument-exception-unsupported-hmac) suggests to change the hash algorithm to SHA-1. However, another error pop up. How can i fix this issues? Thanks and have a good day!