iPad mini 3 won't accept my Apple ID's password

I have a mini iPad 3 that hasn't been updated for so many years now. It works fine but an apple id sign in keeps popping up. I tried everything, i did sign an apple id but it keep saying that the password is wrong. My apple id works perfectly fine with my other apple products. Yes, i need to upgrade but i just can't, this iPad has a sentimental value. Please help

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