password policy is empty.

Step 8: Checking few other requirements…
OK: nmap is present.
OK: ssh-keygen found, LSC credential generation for GNU/Linux targets is likely to work.
WARNING: Could not find makensis binary, LSC credential package generation for Microsoft Windows targets will not work.
SUGGEST: Install nsis.
OK: xsltproc found.
WARNING: Your password policy is empty.
SUGGEST: Edit the /etc/gvm/pwpolicy.conf file to set a password policy.
Step 9: Checking greenbone-security-assistant…
OK: greenbone-security-assistant is installed

how do i fix this ??

Tried what the output of that used script is already suggesting?