To print a 3D file on the Ultimakers or Anycubic printer, you need to use Cura, a free, well supported slicer made by Ultimaker. You can access this program on the laptop in the Makerspace, or you can download it on your computer: https://ultimaker.com/en/products/cura-software
To print, you must select the correct printer in Cura, make sure your material is set to PLA (unless you specifically choose a different plastic and change the filament in the printer), and click “Slice,” and then “Save to external disk.” For the Ultimaker 3 Extended, you must connect the USB flash drive from the printer, or for the Ultimaker 2 Extended + or Anycubic Kobra Max, you must connect the printer’s SD card. If your computer doesn’t have an SD card slot, you can use one of the adapters in the Makerspace to connect it.