Recently widowed neighbor wants me to fix her Macbook Pro 15

[chopper]

I cleared everything off the other user/her account. She says she doesn't use the Macbook for anything but "internet".

I am signed into icloud on the pref panel.

I'm trying to sign into the App store to try and download a newer OS but I get a spinning beach ball when doing so in the App Store app.

Restart/sign out/sign in repeat no joy.

Is there any way to get an installer on a thumb drive or anything?

I can access app store on "my" computer and my phone, oddly.

Keyboard works and seems quite nice. In fact the whole computer seems very nice.