Access token must be provided. Ensure the access token has been fetched first.

[jellinghausen]

Access token must be provided. Ensure the access token has been fetched first.
Parameter name: oauth2AccessToken
at Nightingale.Core.Client.NightingaleClient.SetAuth(Item, HttpRequestMessage) + 0x578
at Nightingale.Core.Client.NightingaleClient.d__10.MoveNext() + 0x203
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() + 0x21
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task) + 0x70
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task) + 0x38
at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task) + 0x17
at Nightingale.Core.Client.NightingaleClient.d__8.MoveNext() + 0x153
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() + 0x21
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task) + 0x70
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task) + 0x38
at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task) + 0x17
at Nightingale.Core.Services.RequestSender.d__5.MoveNext() + 0x156

How do I provide the access token first?