ubuntu-21.04-live-server-amd64.iso

Run this command in your terminal in the directory the iso was downloaded to verify the SHA256 checksum: echo "e4089c47104375b59951bad6c7b3ee5d9f6d80bfac4597e43a716bb8f5c1f3b0 *ubuntu-21.04-live-server-amd64.iso" | shasum -a 256 --check

You should get the following output: ubuntu-21.04-live-server-amd64.iso: OK

Or follow this tutorial to learn how to verify downloads