I looked into their website to know how they have done it. They achieved this effect using the CSS property background-clip. Here we use background-clip: text; property. You can find more about this property here. Note: this feature is not supported in IE11. A preview of this can find here.
Logic: You can apply the transparent image for the background property. Better wrap the text content with a parent and apply the background to that. Then apply the background-clip: text; property to that wrap. As a fallback, you can give color property too.
Try it and let me know if you guys face any issues, Happy to help