If you get Universal Credit (UC) do not download a universal credit (UC) app – it’s a fake and by downloading it you could be at risk of identity theft and fraud. Do not respond to any text claiming to be from UC - these are fake too.
The only secure way to access your account is through the Department for Work and Pensions (DWP) website: https://www.gov.uk/sign-in-universal-credit
DWP will only ever ask you for information via this website.