Here are the permissions needed to add and verify Facebook/Instagram sources in the source management.
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First of all, here is where you can view your permissions:

The first permission that is needed for all of the channels is the Business account "Basic" permission. You would need to gain this permission from the source itself. Otherwise, you can create/connect the sources to the asset groups:
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Here is how you can create and assign sources to the asset group:

​Note: ​Please make sure that the Facebook account has access to the specific asset group to which the source is connected.

For Facebook Ads, at least "View Performance" permission would be needed:

For Facebook Page "Insights" permission is needed:

For Instagram, you would need to have "Insights" permissions to the linked Facebook Page(they would need to be under the same Account Centre) and also "Insights" permission for the Instagram account: