So refreshing to find someone else using Triodos!
Chances are you have to use a digipass to get into internet banking (username & password access is for personal savings only) and so, if you could use Yodlee you'd have to login each time with the digipass rather than use the auto feeds. So, given how Yodlee is not 100% reliable, you are probably better off using the bank statement download/upload.
I tried to set it up Yodlee on mine but unfortunately got a "WHOOPS!" so couldn't try it out but as the screen above is asking for username & password, it's almost certainly only available in the Netherlands and so you're probably better off asking Triodos UK whether they are going to allow Yodlee to access UK current accounts.