Let’s assume your Ubuntu iso is in your Downloads folder
(a) Open Powershell
Get-FileHash C:\Users\username\Downloads\ubuntu-24.04.3-desktop-amd64.iso
Replace username with your Windows 11 username
Replace iso file with your complete file name
e.g. xubuntu-24.04.3-desktop-amd64.iso
Tap Enter to start the command
Wait patiently
Highlight the Hash output
Copy with Ctrl c
(b) Open Notepad
Paste the Powershell output checksum on line 1
Copy & paste the relevant hash from the website below on line 2
Example herewith
FAABCF33AE53976D2B8207A001FF32F4E5DAAE013505AC7188C9EA63988F8328
faabcf33ae53976d2b8207a001ff32f4e5daae013505ac7188c9ea63988f8328 *ubuntu-24.04.3-desktop-amd64.iso
Powershell outputs in upper case - quelle surprise!
Ubuntu family sha256sums here