It depends on the projection of the original map.
It might not be possible to get an exact fit. The more points you can georeference in MapTiler the better the fit could be. Can you add more than three points?
You could perhaps also try doing it directly in Google Earth
sometimes that works (see the tip about using 'manial coordinates for each corner' - the button is actully called 'switch to latlongquad')
... maybe see if can find an unprojected/plate carree/equirectangular version. That should work directly in Google Earth.
could also maybe look for a KML version, then vector features will automatically be transformed into the right projection