Since the Library closed I have received a few enquiries from Economists asking about getting into The Economist (full text and graphics version) now we are all off campus. I have tried it myself on my home laptop and I also had problems - now resolved!
Here is my advice:
Follow the link from either the eresources AZ list or the link from the CJBS Information Centre databases page. This is the link you need: https://proxy.jbs.cam.ac.uk/login?url=https://www.economist.com/
Access is authenticated through our proxy server - unless you go through the link the Economist has no way of knowing who you are. This link is the only way for them to pick up Raven credentials from your computer. So clicking here in a new browser window should prompt you to login via Raven and you should no longer see a request to login half way down the page as you scroll through an article. N.B. Even when logged in this way you will always see subscribe and login buttons at the top but if you can click on an article and read it all the way through you are in.
If you are still having problems open a different browser - it works best in Chrome or Firefox. Try clearing cookies and cache and try again. I have a Mac and I understand many people are accessing it with no problem via Safari. However, in the end, what worked for me was downloading Chrome to my MacBook.
Remember you can always access the text only Proquest access to The Economist. Just go into iDiscover and login. Search for 'The Economist' and it should be one of the first hits - follow the links through. Unfortunately this subscription will not show images, graphs and graphics.