Windows 10 or 11 (Droylsden M18)

Hi there I'm new to PC's I've built a pc together and I'm in need of windows 10 or 11 so I can get it up and running for our daughter who has an illness and I'm struggling trying to get a copy of windows so I can get it all completed and then she has something to go on and pass her time she has Cerebral palsy so limited what she can do we would be so grateful to whoever can help out with this matter many thanks