Hi there, BitLocker is designed by Microsoft and iPad is a product of Apple, so it's normal that your iPad cannot open a BitLocker encrypted USB drive. The right way is to unlock your BitLocker encrypted drive on a Mac because there is iBoysoft BitLocker for Mac allowing you to do so.
Or, you can connect your encrypted drive to a PC and then turn BitLocker off, and then use the USB drive on your iPad Pro.