What seems to be the trouble when you're trying to use the keyboard? Do you get to a specific point that indicates a technical problem or do you just seem to need some help on using a MIDI keyboard with Music Maker? Please try following my instructions below. If you have problems at any point during that procedure, just let me know and tell me what the issue is and how the program doesn't behave as expected.
Start up Music Maker 14. Open the program settings ("Audio/MIDI tab") by pressing the "P" key on your computer keyboard. Double-check that the proper driver appears in the "Input device" drop-down list under the MIDI section. Now, find the VSTi object in the "Synthesizer" tab and drag & drop it up into one of the tracks to create a Midi object. When you release the mouse button, a drop-down menu should come up, where you can pick the VST instrument associated with this Midi track. Pick one of the Vital or Revolta 2 instruments, just for the purpose of testing. Now the actual Midi Editor should open up, where you can edit the Midi track. You should now (while the Midi Editor is open) be able to hear your input from the keyboard being replayed by the VST instruments you have chosen. You can also change that VST instrument again in the Midi Editor, using the "Instr." drop-down list at the top. Once you're done testing and setting up everything, you can start recording your Midi track.
On a side note: You might want to make sure that your Music Maker is configured to use an ASIO driver to avoid latency related problems. You can change the driver model when you're in the main screen of Music Maker and press "P" on your computer's keyboard to bring up the "Playback parameters" dialogue. Pick "ASIO" under "Device" and choose a suitable ASIO driver from the two drop-down lists. If your sound hardware doesn't provide ASIO drivers, you can opt for the generic "Magix Low Latency (2008)" driver.