Connect the b-l072z-lrwan1 to the things network V3

That’s what many will probably use with it.
However, it is also possible to develop for this board using the Arduino framework and the MCCI LMIC LoRaWAN library.

LMIC-node is an example program for implementing a node for The Things Network. It uses the Arduino framework and the LMIC LoRaWAN library. LMIC-node also supports the
B-L072Z-LRWAN1 board and works with TTN V3.

However, which development framework to use will depend on the requirements (which have not yet been made clear).