Perhaps your method is wrong, 
try to compare what you are doing with this example in Linux:
chimp@laptop $:sha256sum e-0.14-o-2021012798648-dev-a3xeltexx.zip
53af25b3d07652ddf386a56b90d0962942234df073cb528668df63e41de06636 e-0.14-o-2021012798648-dev-a3xeltexx.zip
chimp@laptop $:cat e-0.14-o-2021012798648-dev-a3xeltexx.zip.sha256sum
53af25b3d07652ddf386a56b90d0962942234df073cb528668df63e41de06636 e-0.14-o-2021012798648-dev-a3xeltexx.zip
I run the sha256sum command against the “file”.zip
Then I expect to get same string returned by cat “file”.zip.sha256sum.
cat reveals the text contents of the “file”.zip.sha256sum
You will find you could alternatively open the “file”.zip.sha256sum in a notepad editor to reveal its contents.