My iPhone 6s plus carrier is cricket 26.1 but when I use the cricket sim it does not work. What is up with that?

It use to be a t-mobile carrier but after I tried to unlock it with the cricket sim, the carrier suddenly changed to cricket 29.1 but it still did not work.

I don't know how you "tried to unlock it with the Cricket SIM". Its not a matter of sticking in another SIM & it unlocks. You have to either request it from your current carrier or through a 3rd party service.