Where is a transfusion usually done? At a hospital?

Outpatient. Blood transfusions can be given in a hospital as well as outpatient infusion centers.
Hospital/clinic/ inf. Transfusions are commonly given in hospitals, infusion centers, and clinics depending upon the availability of properly trained staff, availability of emergency assistance in case of reactions, distance from blood bank, etc.
Typically or clinic. Blood transfusions are typically done in hospitalized patients, but they might also be done in an ambulatory or outpatient setting. Examples of outpatient settings where this might occur, could be a hematology-oncology clinic or a dialysis center.
Infusion ctr/hosp. Blood transfusion is usually done at the out patient infusion center , in the hospital, or at the blood bank.