@Jurirat-Team0
It's not uncommon for Airbnb to investigate and/or process a claim from a guest without any communication or indication to the host. Often the host finds out they've been suspended or otherwise penalised ... by stumbling on it. You open the app one morning and your listing(s) are blocked, without any explanation. And if you try to get answers from support, they can't or won't explain anything.
The same thing happens to guests. A booking cancelled for no apparent reason, without communication with the host or guest. Getting an explanation can be difficult or impossible.
So, I'd be inclined to count your blessings on this one. At least they've given you some chance to give evidence of your side of the story.
If this is a claim you made against a guest, then again you should be pleased that AirCover is actually asking for documentation rather than completely dismissing it without further discussion, which does happen often enough.
AirCover is not a guarantee or insurance, and they have no obligation to even accept any claim, let alone give you the opportunity to provide proof of it. Even after delivering irrefutable proof with every detail they ask for, they may very well deny any compensation and permanently close the case, or reduce it to a minimal amount.
It's always wise to have an insurance policy, rather than relying on the platform.
Good luck and happy hosting.