how did hitler's ambitions cause the second world war

As Hitler came to power in Europe, he laid out a series of goals for the German nation. Many of Hitler's goals sought to address the Treaty of Versailles. Hitler, and many Germans, felt that the Treaty of Versailles was unfair toward the German people.
The Treaty of Versailles was signed at the end of World War I, and it placed primary blame for the war on Germany through a clause referred to as the "War Guilt Clause." The Treaty of Versailles also forced Germany to pay massive reparations for the war, an agreement that would be very damaging to the German economy. Another aspect of the Treaty of Versailles involved Germany giving up territory to its neighbors. Much of the surrendered territory contained a large population of ethnic Germans. Finally, tremendous limits were placed on Germany's military. The Allied powers of World War I, particularly Britain and France, were fearful that Germany would become aggressive again if it was allowed to maintain a large military. Thus, under the treaty, the German army would need to remain under 100,000 men in size. Germany would also not be allowed to maintain large ships or submarines for its navy. Additionally, it was prohibited from having an air force.
Hitler's goals for Germany included ending or destroying the Treaty of Versailles. As I previously stated, this goal was popular amongst the German people, as they felt that Germany was being unfairly and harshly punished for World War I. Hitler also hoped to form a "Greater Germany," or Großdeutschland, which would be a country for all ethnic Germans. Through his plans to create a "Greater Germany," Hitler hoped that all ethnic Germans who had been separated by the territory changes at the end of World War I would be reunited in a single nation. Additionally, Hitler felt that the German people had become too crowded in terms of territory. Hitler hoped to create "living space," or lebensraum, for the German people by conquering new territory, primarily in Eastern Europe. Hitler believed that lebensraum was necessary for the ethnic German people to thrive.
As you can see, Hitler's goals were aggressive, and one can conclude that they would eventually lead to conflict. Upon taking power, Hitler would work to accomplish his goals. First, he would rearm the German military (in violation of the Treaty of Versailles). Next, he would create a union with Austria, a country of primarily ethnic Germans. At this time, Germany was not yet very strong and, many historians argue, could have been stopped through intervention by other European nations and the United States.
After testing the reaction of the international community, Hitler set his sights on the Sudetenland in Czechoslovakia. The Sudetenland was an area of Czechoslovakia where many ethnic Germans lived. As part of his goal to unite all ethnic Germans, Hitler annexed the Sudetenland. British and French leaders had met with Hitler regarding the annexation, but with both nations fearing another war (this was only about twenty years after World War I had ended), they allowed Hitler to take the Sudetenland. The policy employed by the French and British is known as "appeasement" and is often cited as a cause for World War II, along with Hitler's aggression.
On September 1, 1939, the year after the annexation of the Sudetenland, Hitler once again sought to accomplish his goals. This time he sought to expand German territory through the invasion of Poland. It was shortly after this invasion that Britain and France finally declared war on Germany. This event is generally cited as the start of World War II in Europe, but it is clear that the conflict had been brewing for years prior. Hitler's aggressive goals of destroying the Treaty of Versailles, creating a "Greater Germany," and gaining lebensraum for the German people ultimately put Germany on a path for conflict. One could argue that the reason World War II was so large, however, was not just because of Germany's aggression, but also because of the lack of early intervention by nations like Britain and France.
https://encyclopedia.ushmm.org/content/en/article/treaty-of-versailles

https://www.bbc.co.uk/bitesize/subjects/zj26n39