Hello Nieboerb,
In most cases, this error means there is something wrong with your credential.
It could be that your application in Azure lacks the necessary permissions, that you have the wrong client secret, or that there is something wrong with the certificate if you are using one. The best thing to do is go over the KB article again on how to set up your application in Azure and check your credentials.
Scan mobile devices through Microsoft Intune - Lansweeper
If you keep struggling with it, it is best to contact Lansweeper Support.
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