We donate blood for free. Does the hospital provide this blood to patients for free?

Wrong concept!

Donate blood to the blood bank (not to the hospital)!

If a patient needs blood, the doctor needs to apply to the hospital's blood bank, and then the hospital's blood bank applies to the local blood station. Only if the blood station agrees, the patient can use blood

Free blood donation is glorious! However, the blood bank needs to do some related testing, separation, storage, packaging, etc. for the blood donated free of charge, and these require fees.