Custom service for BLE connection

Hi everyone,

I am trying to understand how I can make an application to use the notifications of BLE services.

For example,
Using nRF Connect apk I can connect to a tag, subscribe to a service and get the data I need. Then all I need is to receive exactly the same data in my apk (in C ++ if possible).
In summary, I need to always connect to the same feature of the same service, specifically UUID 003bbdf2-c634-4b3d-ab56-7ec889b89a37 of 680c21d9-c946-4c1f-9c11-baa1c21329e7, of a specific tag.

Has anyone done something similar or knows where to start?