Either you tried to install ISPConfig in a existing mysql DB or your mysql password contained special chars or the mysql user did not had admin priveliges.
Please remove ISPConfig by running:
rm -rf /root/ispconfig
rm -rf /home/admispconfig
and delete the ispconfig mysql database. Then unpack and reinstall ISPConfig and make sure that 1) The database does not exist already, 2) The mysql root password does not contain special chars that might be interpreted on the shell and 3) That you use a mysql user with root priveliges.