You’ll not be able to directly access your iPad encrypted filesystem from an Android device connected via a USB cable.
If you wish to transfer files and data with any non-Apple computer, the are three relatively simple and accessible methods:
1) Use iCloud to make files and data accessible to other computers. From your Android device, using any web browser, sign-in to your iCloud account:
https://icloud.apple.com
From here you will be able to access many aspects of your iCloud services - and files/photos that you have stored/shared via your iCloud account.
2) You might consider transferring data using an intermediate USB storage device - such as a thumb-drive.
Depending upon your iPad model, you may need an appropriate adapter to connect your USB storage to your iPad. If your iPad has a Lightning connector, you will require an Apple Lightning to USB 3 Camera Adapter:
https://store.apple.com/uk/xc/product/MK0W2ZM/A
3) You can also install a third-party File Manager App on your iPad that incorporates an SMB File Server - that can be accessed by other devices over a WiFi connection.
One App that comes readily to mind is FileBrowser Professional by Stratospherix:
https://apps.apple.com/gb/app/filebrowser-professional/id854618029
You would be well advised to review the extensive online Manual and help files to determine suitability for your needs.
https://www.stratospherix.com/products/filebrowserprofessional/filebrowser-professional-user-guide.php