So they were build for ICU overflow (COVID) but they didn't have adequate equipment for critical care?
Most of these field hospitals were not ICU or critical care facilities. Most came from private organizations such as Samaritan's Purse. Samaritan’s Purse had one of the most advanced facilities with 68 beds and 10 ICU beds with ventilators in NYC early in 2020. Their primary issue was staffing - a staff of 70 is necessary for the field facility.
Of course people opposing this hospital because of the organization's ties to Franklin Graham made it close down.