It's important to note that there are two countries with "Congo" in their names:
* Republic of Congo (also known as Congo-Brazzaville)
* Democratic Republic of Congo (also known as Congo-Kinshasa)
Both countries use the same proper adjective, Congolese.
To avoid confusion, it's best to refer to the specific country by its full name, for example:
* "The people of the Republic of Congo are known as Congolese."
* "The capital of the Democratic Republic of Congo is Kinshasa."