ubuntu-21.04-desktop-amd64.iso

Run this command in your terminal in the directory the iso was downloaded to verify the SHA256 checksum: echo "fa95fb748b34d470a7cfa5e3c1c8fa1163e2dc340cd5a60f7ece9dc963ecdf88 *ubuntu-21.04-desktop-amd64.iso" | shasum -a 256 --check

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

Or follow this tutorial to learn how to verify downloads