The accept button is disabled because you opened the invitation link while logged into the same account that sent the invitation—you can't add yourself as a team member to your own account.

To fix this:
1. Open the invitation link in a private/incognito window or a different browser
2. Sign up with a different email address
3. Then accept the invitation

Thanks for the review—I hope you're enjoying Invoiless! For any technical questions, please open a ticket or send us an email for faster support and follow-up. 🧡