According to Atlassian in order to use the organizations or user REST API you must have a valid API key and your domain to be verified(your users accounts need to be managed accounts).
https://developer.atlassian.com/cloud/admin/organization/rest/intro/
That is why Timescale needs an API Key to get this data.
STEPS:
To create an API key:
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Go to admin.atlassian.com. Select your organization if you have more than one.
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Select Settings > API keys.
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Select Create API key in the top right.
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Enter a name that you’ll remember to identify the API key.
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By default, the key expires one week from today. So make sure you change the expiration date to bigger period like an year. This needs to be re generated once per year
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Select Create.
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Click Done
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Copy the API KEY and place it in Timescale/Overall Settings/Atlassian Api Key. Hit Update Button.
9.Verify your domain to manage accounts
https://support.atlassian.com/user-management/docs/verify-a-domain-to-manage-accounts/