Hello Axi, thank you for downloading Boss Cart JV. Please make sure that the /administrator/components/com_sef/security/sh404SEF_AntiFlood_Data.dat file exists on your hosting space. I have the strong guess that during the file transfer this file haven't been uploaded and that is the reason why you see this warning message.
Thanks

you will need to log into your hosting control panel and create a mysql databse

if you are using cpanel iy would be listed under databases

you will need to make a name for your database

so it would look like username_databasename

hope this helps

once you have created the database simply create a user for that database