Wil it go into gear?
A couple things come to mind
Did you hear/feel the torque converter go on all the way like two clunks?
And you should have had to pull it toward the engine slightly to bolt it to the flex plate.
Also could be the wrong spline converter
Just spinning around the input shaft.
That was why I asked if it will go into gear.
First two things I'd look into.
Hope you find it