The import button may not work at the moment. You should however be able to login and export in two steps. This was reported last week but we haven’t had a chance to look at this any further right now.
We’ve just published an update to the Chrome store which fixes this problem. Basically Santander replaced the old link to view transactions with a new drop-down menu:
Our code was still looking for the old link, hence the error. The update should propagate in about 2-3 hours.