USB stick "this accessory requires too much power"

Which adapter? It sounds like you need the equivalent of a powered hub where you can power the drive while connecting the cable which is then used for data transfer alone without drawing power from your device. Kind of along the lines of:

Lightning to USB 3 Camera Adapter - Apple

You then attach a proper power source such as your usual charger to this while also attaching the drive to the device.

You provide no information as to what, precisely, you are attempting to connect to your iPad.

If connecting external USB devices, you’ll require an Apple Lightning to USB3 Camera Adapter:

https://store.apple.com/uk/xc/product/MK0W2ZM/A

To provide sufficient power for many USB devices, or external storage drives, you’ll need to connect a Power Adapter (charger) rated at least 12W to the auxiliary Lightning port of the Camera Adapter. The iPad, on its own, except for very low power devices, cannot supply adequate power for connected USB storage devices. The Power Adapter supplied with your iPad, with the appropriate cable, is likely to be adequate.

Alternatively, power for externally connected devices can be provided by a powered USB - to which you connect both the iPad (using the Lightning to USB3 Camera Adapter) and the needed USB accessory.

This external website may provide some additional clarity:

https://www.lifewire.com/how-to-connect-usb-devices-to-ipad-1999862

I hope this insight and information proves to be helpful to you - if only in promoting some additional thought as to your needs. If you have further questions, please don’t hesitate to ask.