I don’t have a computer and I cannot Activate the iPad

Hi jessechima10,

Welcome to the Apple Community.

If the activation lock is on, on your sister's iPad:

you would need the Apple ID tand password o unlock it, or update it.

The article (link below) explains how activation lock works:

Activation Lock for iPhone, iPad, and iPod touch

https://support.apple.com/en-us/HT201365

This other article tells:

How to remove Activation Lock:

https://support.apple.com/en-gb/HT201441

Hope this helps you :)

PS:

If the iPad is not locked,

you might want to try steps in this article:

Set up your iPhone, iPad, or iPod touch

https://support.apple.com/en-us/HT202033