Please read following link, it might be helpful.
https://download.milestonesys.com/MIPSDK/Samples/TriggerAlarmFromExternal-ConceptSolution.pdf
Please see this sample and read instructions there.
Also please read this answer in the post - https://developer.milestonesys.com/s/question/0D53X0000A0qXGkSQM/we-have-an-integration-of-which-the-client-cannot-see-our-integrations-alarms-in-the-alarm-manager