Any bid application may be accepted or rejected by the seller.
The seller has the final say about which bids or offers are accepted and rejected - up to a point. Flippa will automatically reject a bid or offer if the seller doesn't accept or reject it within 72 hours.
If your bid or offer was rejected, it means that the seller has chosen not to put that bid or offer in the running to win the auction or sale. The seller might reject your bid application for any number of reasons:
The seller hasn't had contact from you, and doesn't know who you are.
In a private sale, the seller has received offers that they prefer over yours.
The seller doesn't want to sell the property to you - perhaps your existing property competes with it, or the seller wants someone with different experience from yours to own the property.
If you're not sure why your bid or offer was rejected, ask the seller. Perhaps they would like to know more about you before accepting your bid or offer.