Error while running make build command

I am following the link. After running make build command it throws me this error :

Fetch or update ploneconf.site
Cloning.
Traceback (most recent call last):
File "/home/onlykingkd/training/backend/venv/bin/mxdev", line 8, in
sys.exit(main())
File "/home/onlykingkd/training/backend/venv/lib/python3.10/site-packages/mxdev.py", line 436, in main
fetch(state)
File "/home/onlykingkd/training/backend/venv/lib/python3.10/site-packages/mxdev.py", line 351, in fetch
repo.update_repo()
File "/home/onlykingkd/training/backend/venv/lib/python3.10/site-packages/libvcs/git.py", line 189, in update_repo
self.obtain()
File "/home/onlykingkd/training/backend/venv/lib/python3.10/site-packages/libvcs/git.py", line 178, in obtain
self.run(cmd, log_in_real_time=True)
File "/home/onlykingkd/training/backend/venv/lib/python3.10/site-packages/libvcs/base.py", line 119, in run
return run(
File "/home/onlykingkd/training/backend/venv/lib/python3.10/site-packages/libvcs/util.py", line 200, in run
raise exc.CommandError(output=output, returncode=code, cmd=cmd)
libvcs.exc.CommandError: Command failed with code 128: git clone --progress ssh://git@github.com/collective/ploneconf.site.git /home/onlykingkd/training/backend/sources/ploneconf.site
Cloning into '/home/onlykingkd/training/backend/sources/ploneconf.site'...git@github.com: Permission denied (publickey).fatal: Could not read from remote repository.Please make sure you have the correct access rightsand the repository exists.
make: *** [Makefile:40: build] Error 1

This error was resolved after I added SSH Key to my github acount
link