Hi Simran!
I am unsure if you can directly bring/import those designs in mendix
However, these might help better understand how to translate those designs into mendix:
https://community.mendix.com/link/space/ui-&-front-end/questions/105924
https://docs.mendix.com/howto/front-end/figma-ui-kit/
Cheers
The key is to open Mendix Atlas UI KIT in Figma (you can find the UI Kit on Figma pages, just google the name). In the UI kit, you create a new page and start designing. You use assets from the kit so your design fits Atlas in Mendix. After the design is done, it is best to create UI Resources Package (UIRP) in your Mendix app (see the Mendix docs). That is just a special module where your "theme" will be stored. In the UIRP you create your page and popup layouts and start designing. You essentially change how Mendix widgets look by using SCSS.