jQuery('.testimonialsSlider').slick({
  slidesToShow: 1,
  slidesToScroll: 1,
  arrows: true,
  prevArrow: "<button type='button' class='slick-prev pull-left'><span class='list-icon fas fa-chevron-left'></span></button>",
  nextArrow: "<button type='button' class='slick-next pull-right'><span class='list-icon fas fa-chevron-right'></span></button>",
  dots: false,
  autoplay: false,
  autoplaySpeed: 2000,
  infinite: true,
  adaptiveHeight: false,

  responsive: [
    {
      breakpoint: 1024,
      settings: {
        slidesToShow: 1,
        slidesToScroll: 1,
      }
    },
    {
      breakpoint: 768,
      settings: {
        slidesToShow: 1,
        slidesToScroll: 1
      }
    },
    {
      breakpoint: 480,
      settings: {
        slidesToShow: 1,
        slidesToScroll: 1
      }
    }
  ]
});

For arrows copy paste this link in header.php
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.4/css/all.min.css" />