First you'll need the axshare link of your Axure RP file. You can view this link at any time in the Publish → Publish to Axure Cloud menu in Axure RP and in your list of projects at app.axure.cloud.
Once you have the link, head over to UXfolio:
- Open your case study in edit mode.
- Add a Prototype section.
- Choose Figma from the list.
- Paste your Prototype code into the box.
- Hit Embed.