Without knowing the exact message SAMM issued, I can't be sure where you are in the program.
However, generally, if SAMM can't find the SDK, it asks you to locate modeldef.xml and, immediately upon closing the message box, an Open File Dialog is displayed allowing you to do so. If SAMM does "know" where the SDK is located, it "assumes" that file is in the standard location. If it's not there, you will get another error message. I suspect, but can't be sure, you are experiencing the second message. If so, check to ensure that modeldef.xml is in the SDK Environment Kit\Modeling SDK\bin folder.
Don