Hello there,
Actually there is too many way to define your rotation to your root joint (scripts, controllers etc.).Usualy, for example; If you already have turn animation for 90 or 180 degrees, first you can open time editor in maya and select your root bone which is usualy hips or pelvis then 'in file option you can select add animation from scene selection' so you can take your animation in Time editor.After that you can click Relocator button (https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2020/ENU/Maya-Ani....)
When you done with relocator (just key the first frame and in the last frame set the animation looks forward exaclty in the first frame )
And then
please watch this video to create root joint and using the script in that video ; (for unreal just get 90 degree on X axis and dont forget to use Freeze rotation after that)
https://www.youtube.com/watch?v=mMYg0N8dKSg&feature=emb_title
You can find the script attached to that youtube video.You will change the joint names in that script and just run it when you done with naming.
After all done, just key the first frame and in last frame key it for 180 or 90 degree depending your animation.It seems like complicated but I am sure you will handle with those links.
Also sorry about my grammer mistakes, English is not my native language.
I hope it will help you If you have any problem just post here I will answer or get video about that for you.
Cheers.
