Error 401 when using Access Token created via High Trust Add-in

[ivanmaria]

I created a high trust add-in for SharePoint OnPrem 2016 by following these steps:
https://docs.microsoft.com/en-us/sharepoint/dev/sp-add-ins/create-high-trust-sharepoint-add-ins

I could successfully create access token for an user. However when I try to access any REST API via Postman, I get the following error message

Request:

GET http://<site url>/_api/web/lists
Authorization: Bearer eyJhb...

Response:

401 UNAUTHORIZED

However, I observed that if 'Anonymous Authentication' is enabled in IIS for SharePoint web application then I am able to access the above REST API but if the 'Anonymous Authentication' is disabled in IIS then I receive 401 UNAUTHORIZED error.

Is Anonymous Authentication a prerequisite for REST APIs in SharePoint on-premise? If not, how do I access REST APIs for high-trust add-in without anonymous authentication?

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Document Details

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• ID: 8e75f802-f01c-d319-5326-ce36804ad2be
• Version Independent ID: f5328b3d-41a7-9c98-0110-865ff4273bfc
• Content: Create and use access tokens in provider-hosted high-trust SharePoint Add-ins
• Content Source: docs/sp-add-ins/create-and-use-access-tokens-in-provider-hosted-high-trust-sharepoint-add-ins.md
• Product: sharepoint
• GitHub Login: @VesaJuvonen
• Microsoft Alias: vesaj

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