The MyHeritage DNA Matching feature uses autosomal DNA - inherited from your mother and father, your four grandparents, eight great-grandparents, and so on - to provide you with a breakdown of your ethnic percentages and connect you with relatives descended from any of your ancestral lines, within approximately the last 6 generations. Non-autosomal DNA test results, stemming from Y-DNA or mtDNA tests, are based on markers, which can not be used for DNA matching.
For further information on how MyHeritage calculates the potential relationship of DNA Matches, please read: What is the cM Explainer™ and how does it predict my relationship with my DNA Matches?