Hi Mario, you are calculating the checksum of the CHECKSUM file itself, instead of using the checksums in the CHECKSUM file to verify another file (the ISO). The -c option in the instructions is important and can’t be ignored.
However, you can also manually read the contents of the CHECKSUM file as Vladislav mentioned. You already calculated the checksum of the ISO here:
xxx@Mac-xxx ~ % shasum -a 256 /Users/xxx/Downloads/Fedora-Workstation-Live-x86_64-38-1.6.iso /Users/xxx/Downloads/Fedora-Workstation-38-1.6-x86_64-CHECKSUM
7a444a2e19012023bf0b015ae30135bafc5fd20f4f333310d42b118745093992 /Users/xxx/Downloads/Fedora-Workstation-Live-x86_64-38-1.6.iso
So you know the ISO has a SHA256 checksum of 7a444a2e19012023bf0b015ae30135bafc5fd20f4f333310d42b118745093992
Now compare it with the contents of the CHECKSUM file by opening it in a text editor. I will show it here, but you should do it on your own too:
# Fedora-Workstation-Live-x86_64-38-1.6.iso: 2099451904 bytes
SHA256 (Fedora-Workstation-Live-x86_64-38-1.6.iso) = 7a444a2e19012023bf0b015ae30135bafc5fd20f4f333310d42b118745093992
Visually checking it is hard, so the better way is to copy the checksum that you calculated from the terminal, then use the text editor’s Search feature and paste it in the search field. It should be an exact match.