Go to Settings, Update & security, Windows Insider Program. Click “Get Started” and follow the on-screen prompts.
Step 4: Select your Insider level
To get access to Paint 3D Preview you will need to choose between the Slow or Fast ring. The Slow ring is ideal for users you merely want to check out new features like Paint 3D while the Fast ring is reserved for more advanced users who want to check out the latest changes and are happy dealing with any software bugs that arise.
Step 5: Compatibility check
A compatibility check will run in the background and register your PC with Microsoft’s build release system.
Step 6: Process complete
Once the steps are completed, your PC will now be targeted to receive Insider Preview builds.
Note: This could take up to 24 hours to happen.
Step 7: Download Paint 3D Preview
Once your PC has completed the update, you can head over to the Windows Store and download the Paint 3D Preview.