This type of error has been reported in the past, for example here: https://github.com/PLCnext/PLCnext_CLI/issues/14
What version of the Toolchain are you using?
If it still does not work with the latest toolchain (2024.0), then please report it on Github.
Here is a workaround:
* Execute the SDK script on the command-line, not using the PLCnext CLI. You will be asked for an installation directory.
* Once the SDK is installed, you can use this command to register the SDK with the plcncli:
plcncli set setting SdkPaths Path/to/sdk --add