Here, you can see how to download a key pair from AWS in simple steps:
Step 1: Open the Amazon EC2 console in AWS.

Step 2: In the left menu, choose Network & Security, then select Key Pairs.

Step 3: Click Create Key Pair.

Step 4: Enter a name for the key pair.
Step 5: Select the format to save the private key in (usually PEM or PPK).
Step 6: Click Create.

Step 7:It will get downloaded to your laptop.

Step 8: Keep it safe somewhere on your computer because you can't download it again.
For more information on Amazon EC2, you can watch this video or read the full guide here.