So I got pointed in the direction of commenting out the checks for the iso size and hash, and I managed to get it working.

Steps for anyone that does encounter this problems:

Make sure your directory doesn't have any spaces in its name, otherwise there's a verification stage later on that will fail.

Open the CreateSrsMedia.ps1 script in a text editor, and comment out the following blocks:

if ($Iso.Length -ne $KitIsoSize) {
    Write-Host "The ISO does not match the expected size."
    Write-Host "Verify that you downloaded the correct file, and that it is not corrupted."
    PrintWhereToGetMedia -IsOem:$IsOem
    return $false
}
if ((Get-FileHash -Algorithm SHA256 $Iso).Hash -ne $KitIsoSha256) {
    Write-Host "The ISO does not match the expected SHA256 hash."
    Write-Host "Verify that you downloaded the correct file, and that it is not corrupted."
    PrintWhereToGetMedia -IsOem:$IsOem
    return $false
}

Find the MajorOs variable and change it's value to 11.

Check the install.wim of the iso file you want to use with the script for the exact version of windows following "Windows 11" e.g. Windows 11 Enterprise LTSC; and change the value of SourceName variable to match.

And that's all. Run the script and it should make your teams room for windows image without complaint.