[NOT allowing me to use my product key]

Hi bought my ESET internet security last night and

it won't allow me to install the program because it says my product key is invalid

 

I uninstalled my previous version and I reinstalled the one that was on the link in my email

that contained my product key

I UNINSTALLED my mcafee last night becaue I didnt think it would be so hard to get this eset downloaded

Please help me asap as I'm completely unprotected now

 

My username and password also dont work for the install or the website I'm very confused