I have built and implemented two PowerApps in our company and now I want to understand more about the CDS and model driven apps. I created a Trial environment to do the MS App in a Day Training last week and want to try some more things out. I am aware that my Trial environment will only last for 30 days so when I read about creating an Individual Environment for a developer I decided to do that and keep working in that environment. I am trying to copy some of the data structures that I have already been working with in SharePoint into the CDS. I have had some success at this using my Trial Environment, but I cannot even authenticate successfully in the Individual Environment.
I have selected my Individual Environment then selected Data/Data Integration/New data Integration project/Sharepoint Online List which gets me to Connection settings where I enter the SharePoint sitename. It tells me I am not logged in despite the fact I am (in the Trial environment it recognises that I am signed in) so I click on Sign in and then I get the authentication error below:

Why can I do this in a Trial environment but not in the Individual Developer environment? Do I need to delete this environment and start again...and can I?