Most cheap external drives come pre-formatted for Windows or some proprietary scheme the drive maker dreams up.
If the iBook is working, find Disk Utility on it and use that to erase and reformat the drive to Macintosh HFS +. If Disk Utility on the iBook is not working and you have another Mac available, you can use that to similarly reset the drive's formatting to something a Mac can read.
Erase a volume using Disk Utility on Mac - Apple Support
What make and model is the external drive? What macOS version is on the iBook?
Cheap bus-powered drives (get all power from the computer's USB port) may need more power than one port can provide. The options there are a powered USB hub between the drive and computer, or a USB "Y" cable like this: https://eshop.macsales.com/item/OWC/USB2AYMBPB/
The latter gets power to the drive from TWO of the computer's USB ports, not one.