Well, one does have to set up the router before use.
Most often by typing something like http://192.168.1.1 --- & that gets you to the opening screen of the router.... and there's usually "Help Screens" available too.
Just be aware that after inputting the correct 192........ number, I have always found that it takes a looooooong time for the first screen to appear - it's a bit of a shock the first few times I set up a router!
At the very least you have to input your e'mail address and password & save it before rebooting the router.
That ISP Login stays there in the router until you change it, and you never have to do any manual login to your ISP ever again.
Sensible persons also use whatever encryption method it has available to "Scramble" the TX/RX path to your Laptop(s) which then need setting up for the encryption code.
That makes it more difficult for others to probe into your files - or hitch a free ride on your Internet connection.