why can i not redeem me free 1 year apple tv as adviti

It is no longer a free year; it is currently 3 months. Also there has always been a requirement to activate the free offer within 3 months. The following has more information that may help: https://www.apple.com/promo/pdf/EN_US_ATV+_Promo_TandCs.pdf

You can only redeem Apple TV one time with your user name.

I got a year free with my phone and was offered a free year in May with my new iPad but could not active the second offer.

Apple support told me I'd have to create a second user name to activate. Not worth it to me.