You can use the iredmail tools to quickly create a new user including the PureFTP attributes and values.

cd iRedMail-0.5.1/tools
vi create_mail_user_OpenLDAP.sh

LDAP_SUFFIX="dc=example,dc=com" # <- Change the LDAP suffix
BINDPW='passwd'                 # <- The user cn=manager,dc=example,dc=com password
PUREFTPD_INTEGRATION='YES'      # <- Change form NO to YES,enable the pureftp inteegration

Run the script to create the users user1 and user2. By default, the default password is same as the user name.

bash create_mail_user_OpenLDAP.sh example.com user1 user2

adding new entry "ou=Users,domainName=example.com,o=domains,dc=example,dc=com"
ldapadd: Already exists (68)

adding new entry "ou=Groups,domainName=example.com,o=domains,dc=example,dc=com"
ldapadd: Already exists (68)

adding new entry "ou=Aliases,domainName=example.com,o=domains,dc=example,dc=com"
ldapadd: Already exists (68)

adding new entry "mail=user1@example.com,ou=Users,domainName=example.com,o=domains,dc=example,dc=com"

adding new entry "mail=user2@example.com,ou=Users,domainName=example.com,o=domains,dc=example,dc=com"