Why can’t i install it? It says I should be connected to the internet but im already connecting

Yutamo wrote:

i cannot use cellular network or mobile data because it’s saying that i need to update it before I can use it

Solve that first!

Try Settings > General > About and see if you’re promoted to do a cellular update.

If not ...

If you see an Update Failed or Apple Pay Not Available alert after iOS update or restart - Apple Support

Why do we see “No Service” in the upper left of your screenshot? That sure looks like the issue.

What model iPhone?

Update the cellular first

Settings, General, About

Look for cellular update

Or take the SIM out and put it back.

You are confusing cellular updates from your provider with iOS updates from Apple