What this error means
Archive detected your Instagram account during connection, but can't fully connect it because message access is turned off. This permission is required—Archive monitors your Instagram DMs to detect when someone tags your brand in a Story.
Your account will show up greyed out in the connection screen with this message. You can still connect other accounts on the same screen, but this one won't work until the permission is enabled.
How to fix it
You need to allow Facebook access to your Instagram messages. This is done inside Instagram's settings.
On mobile:
Go to your Instagram profile
Select Settings and activity
Under How others can interact with you, select Messages and story replies
Tap Message requests
Under Connected tools, enable Allow access to messages
On desktop (via Facebook):
Log in to Facebook and click your profile icon in the top-right corner, then switch to your Facebook Page
Click the menu icon and select Settings & privacy, then Settings
Scroll down and click Linked accounts
Click Instagram
Toggle "Allow access to Instagram messages in Inbox"
Log in to your Instagram account when prompted to confirm the permission
After enabling it
Go back to Archive and click Reconnect. The account should now appear as connectable.
If it's still greyed out after reconnecting, double-check that the toggle is saved and try logging out of Instagram and back in before reconnecting.