Welcome to the Wefugees Community and thank you for your question.
I made some research and found information on the Website of the Ministry of Foreign Affairs in Montenegro.
Here it says:
"Holders of travel documents issued by the European Union Member States or the United States of America, Kingdom of Norway, Republic of Ireland, Swiss Confederation, Canada, Commonwealth of Australia, New Zealand and Japan based on the Convention Relating to the Status of Refugees (1951) or Convention Relating to the Status of Stateless Persons (1954), as well as Travel Documents for Foreigners may enter, pass through the territory of and stay in Montenegro up to 30 days without a visa."
So if you are holding a travel document issued in Germany, this might apply to you. If you are holding a passport from a third country you need to check the conditions for that respective nationality, I assume.
I hope this helps and please don't hesitate to get back to us with any further questions.
All the best,