You must use a full Mac or Windows PC computer to do the re-formatting of any external drive to use with iPad/iPhone/iOS/iPadOS.
My experiences have recommended that any external drive needing to be used with ANY Apple iPadOS device really needs to be formatted on an Apple Mac computer to ensure/insure correct operation.
If NO Mac computer, find and family member or friend that owns a Mac to possibly help you format this drive
OR
You need to search online for your nearest, “local” Apple store location and call contact phone numbers and call to make an appointment to ANY external drive you have properly format by Apple employees who have access to a Mac.
They will be glad to assist you.
In addition, the external drive needs to be formatted using a single data drive partition into one of these file/data formats below.
Apple Mac computer native drive formats - APFS ( Apple Proprietary File System ) OR Apple HFS+ ( Hierarchical File System+ )
FAT 32
Ex Fat
Apple Website external drive help links here below.
Tap on the links below.
https://support.apple.com/en-gb/guide/ipad/ipad1c415e32/ipados
https://support.apple.com/guide/ipad/external-storage-devices-ipad75b7b23f/14.0/ipados/14.0
