Earlier quoted context omitted.
No party ever held a majority in the Federal Republic of Germany. But the CDU was the largest party in the previous parliament, and part of the governing majority.
There is by definition almost always a party holding a relative majority (more seats than any other party), which the CDU did for the longest time. You are correct that they did not hold an absolute majority (more seats than everybody else combined), ensuring that they always had to form a coalition to achieve that.
Nevertheless, it might be better to use unambiguous terms like "plurality", or define ones terms, when writing for an international audience.