We have had a number of users reporting issues with access to Scopus recently (and now ScienceDirect too) and we have been liaising with their support staff to try to resolve them. We have not yet got to the bottom of the problem but we have found of couple of options that sometimes help.
Often if you just click the X to shut down the error message, it will then give you access anyway.
If you are on campus you should get access automatically.
If you are off campus it will look like this:

Look for the icon that looks like a temple (this means Institution
login). Ignore the Sign in button.

The click Check access.
This brings up a box where you can search for University of
Bedfordshire:

It suggests you can put your email address in this box –
don’t. Just put “Bedfordshire”.

Click Access through your organization and login with your
usual UoB account, if it asks you to. If you have recently logged into another
system, you may not need to.
Hopefully you will now be logged in and good to go!

Another thing that can sometimes work is using a different browser, eg Edge if you usually use Chrome, or using a Private/Incognito tab.
You could also consider using the alternative database Web of Science instead of Scopus.