In FME Desktop I have had succes connecting to a Dynamics 365 test instance using the 'Microsoft Dynamics 365' Web Connection and a simple username/password (and client secret etc. of course). But now I need to connect to our production Dynamics 365 which is set up to use SSO. No matter what username/password I use i the connection I get this error:

Updating access token for 'remu01
Microsoft Dynamics 365'

HTTP Error: 400 - Bad Request

HTTP Error: 400 -
{"error":"invalid_grant","error_description":"AADSTS70002:
Error validating credentials. AADSTS50126: Invalid username or
password\\r\\nTrace ID: fc59aa9f-ed03-4503-b7f6-2efc7aa24c00\\r\\nCorrelation ID:
efcdd9b0-3969-4107-9645-2a69a762f4b6\\r\\nTimestamp: 2017-12-05 11:19:54Z","error_codes":[70002,50126],"timestamp":"2017-12-05
11:19:54Z","trace_id":"fc59aa9f-ed03-4503-b7f6-2efc7aa24c00","correlation_id":"efcdd9b0-3969-4107-9645-2a69a762f4b6"}

Error response: invalid_grant -
AADSTS70002: Error validating credentials. AADSTS50126: Invalid username or
password

Trace ID:
fc59aa9f-ed03-4503-b7f6-2efc7aa24c00

Correlation ID:
efcdd9b0-3969-4107-9645-2a69a762f4b6

Timestamp: 2017-12-05 11:19:54Z

Unable to update access token for
'remu01 Microsoft Dynamics 365'

Access token not found for connection
'remu01 Microsoft Dynamics 365'