pop up attached to war of titans account

hi guys. im sorry im a real newbie in the whole online gaming world and im lost to find a solution to my problem. my friend's war of titans account seems to be connected to a pop up. it doesnt matter from which computer or which operating system and anti-virus he uses, it always appears again. is it possible that the account has a virus attached to it? how could i get rid of it if it is attached virtually to the account? im sorry if i sound really stupid, i just have no idea what to do cause even if i use anti-viruses, malware, spyware removal or block the site , it will still come up if logged from a different pc. does anyone know what i can do? i appreciate any help. thanks a lot

 

What is the message in the popup? Who does it say it's from? Try to take a screenshot, and attach it to your reply.

How to take screenshots

How to attach it