Good afternoon Liam,
Majority of data published via the Defra Data Services Platform is available as Open Data and can be accessed without the need for an account to be created.
Restricted data is available to be used in projects contracted out by Defra bodies. To access such restricted data for specific project, you would need to set up a Defra-body Contractor user account.
Any downloads of restricted data by Contractors will have to be approved by the relevant Project Manager from the Defra body funding the work.
More information about the various user types is available in the following post: https://support.environment.data.gov.uk/hc/en-gb/articles/360000443797-Changes-to-the-Data-Services-Platform-are-coming-soon-.
Hope this helps, but please don't hesitate to contact us if you need any more information or support.