Raspbee2-rtc-master not correct

I’m a complet beginner with Linux and try to set up conbee on my raspberry pi 4. At first I installed the 64-bit Raspberry Pi OS with the Raspberry Pi Imager. Then I installed the iobroker along a tutorial.
Now I would like to install RaspBee II (the element is already attached in my Raspberry). I followed the instructions on RaspBee Installation
It all worked well until the “make” command. Then it throws Error2: /lib/modules/5.15.61-v8+/build is not found.
What did I do wrong? The ls -R command shows the following content:
LICENSE Makefile README.md rtc-pcf85063.c rtc-pcf85063.service

Many thanks for your support

Hello, perhaps HELP: Compiling driver error, no /lib/modules/3.10.25+/build - Raspberry Pi Forums
Or more precise Make fails on 64bit bullseye · Issue #19 · dresden-elektronik/raspbee2-rtc · GitHub

Hi Smanar
Many thanks for your help. Unfortunately, I was not able to fix my problem in that way. I restarted now in an alternative way, setting the image of Phoscon_Gateway_Homebridge_2022-10-27 on my SD card.