Can't download/buy apps on Macbook but OK on ipad (same apple ID)


Jul 4, 2017
Hi, I have just bought a 2nd hand Macbook Pro running El Capitan. I already have an iPad and iPhone and can download both free and paid apps on them. I set the Macbook up on my existing account but when I try to download any app I have to sign in with apple id, this works and I click install then get a message to verify my billing info. I click on this and get an error message on an otherwise blank page as follows :-

Your request produced an error.

I am able to use iCloud drive and iWorks for iCloud so Iam definitely logged in OK and when asked for apple id and password for a (free or paid) app it accepts this then asks to verify billing info, when i click to verify, I get the above error.

Can anyone help, I am new to Macs as I have been a Windows user since Windows 2, I keep hearing about how much better Macs are than a PC and bought this to see if this is right but it's obviously not if I can't add any apps to it. Any idea what I am doing wrong?