Cannot install bacula-client error unknown public key

[Maykel Franco <maykeldebian@xxxxxxxxx>]

Hi, I try install bacula-client in my archlinux but I get this error:

  -> Found bacula-fd.service
==> Validating source files with sha256sums...
    bacula-7.0.5.tar.gz ... Passed
    bacula-7.0.5.tar.gz.sig ... Skipped
    bacula-fd.service ... Passed
==> Verifying source file signatures with gpg...
    bacula-7.0.5.tar.gz ... FAILED (unknown public key 9E98BF3210A792AD)
==> ERROR: One or more PGP signatures could not be verified!
==> ERROR: Makepkg was unable to build bacula-client.
==> Restart building bacula-client ? [y/N]


How can resolve it?

Thanks in advanced.