How do you phrase XXX number of people have Internet addiction in Chinese? I have a phrase： XXX number of people are addicted to the Internet.

I wrote this as: xxx 个人有（InternetAddiction.

Or could I use the phrase 上瘾用网络?

However I am not sure if it is correct grammatically.

XXX 个人上瘾用网络.
A more formal form to say it:

幾千萬人有互聯網依存症 - 'ten of millions of people have Internet Addiction'

A more colloquial way to say it:

幾千萬人上網成癮 - 'ten of millions of people getting online so much it became an addiction to them'
or simply
幾千萬人有上網癮 - 'ten of millions of people have internet addiction'