Just a tip in regards to the digital research center SVAR at the National Archives of Sweden.
Though SVAR offers a range of subscription models for individuals—some free, some for a fee—there is also institutional access available. So, if your university, library or association has a subscription running, you should be able to access the collections by proxying through your institutional Central Authentication Service (CAS), or similar service. This would also effectively eliminate the need to register an individual account, etc.
