Karl Marx was famously opposed to capitalism. He was also opposed to socialism. Opposing both of these economic systems, he advocated only for a communist economic system. Canada has a mixed economy. Canada's economy emphasizes capitalism but is undergirded by socialism in public services.
It is probable that Karl Marx would have been opposed to the structure of Canada's economic system. If you want to separate what he would probably have "thought about Canada" from what he would probably have thought about "our economic system," it is possible that Karl Marx may have observed a system in Canada that works smoothly and efficiently (notwithstanding the variables of economic changes) and is conducive to the happiness and well-being of a preponderance of the population.
Karl Marx thought capitalism should be overturned by a revolution of the proletariat against the capitalists, those who control wealth and access to necessities of life (food, housing, clothing, work). He thought socialism was founded on a philosophy of, as he said, cobwebs and alienation, asserting that socialism deadened the revolt arising from the class struggle (Lewis S. Feuer, "Karl Marx").
Canada encourages private sector growth in products and demand. Canada encourages entrepreneurs to respond to the emergence of new products and to the consumer demand for them by opening new business. These new businesses provide new jobs while meeting consumer demand and while channeling products into the marketplace. In the public sector, Canadian economic policy places the provision of such services as schools, hospitals, roads, sewage systems, medical care, and bridges on the government. These are difficult services to provide and are wanted and needed (demanded) by the population universally. Therefore, government economic policy removes the competition in these and similar services so that all citizens may be served fairly and equitably (Gary Rabbior, "The Canadian Economy").
Consequently, while Karl Marx would reject the economic foundations of Canada's economic system, he may find he is faced with a conundrum to solve because of the prosperity and well-being he observes in Canada. [He may be really flummoxed by an encounter with Denmark's economic system and society.]