The "No Valid Ad Accounts Shared" error usually means ManyChat doesn't have explicit access to your ad account yet, even if you have full control in Business Portfolio.
Try this:
1. Go through the Share Permissions flow — In ManyChat, go to Settings > Messenger > Marketing campaigns tab and click "Share permissions". This opens a Facebook walkthrough where you explicitly grant ManyChat access to your ad account. Just having control in Business Portfolio isn't enough, you need to share it with ManyChat specifically.
2. Verify payment method — Your ad account needs a valid credit card attached from a Meta-supported country. Check in Ads Manager > Billing.
3. Try in Incognito/Private mode — Sometimes cached sessions cause issues. Open ManyChat in a private browser window and try the Share Permissions flow again.
4. Double-check you're selecting the right assets — When going through the Facebook walkthrough, make sure you're selecting the ad account that's in the same Business Portfolio as your page "NVTours - Your Travel Agent"
If none of that works, contact ManyChat support, some ad account issues are Meta-side limitations that only they can escalate.