Either the SPN is missing or duplicate (check the service account used ADFS make sure that ONLY this service account holds the servicePrincipalName with the value HOST/adfs.<yourdomain>.nl.
Or the user-agent is not supported for SSO, in that case you can try the following:
Set-AdfsProperties -WIASupportedUserAgents ((Get-ADFSProperties | Select -ExpandProperty WIASupportedUserAgents) + "Mozilla/5.0")
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