I am creating custom characters, rigging in Accurig, then exporting from Character Creator 4 straight to SketchFab. I can attach motions from Reallusion, but I think that violates the license if I either sell the rigged character or allow a free download. If I try instead to import a Miximo motion and save it as a motion file, for some reason it adds a lot of frames to the motion beyond the end of the movement. I guess it's because of the original project when I imported having more frames than the motion. 
1. Am I missing something with the Miximo import?
2. Are there free motions that I can use from Reallusion even if I allow a free download or sell the model.

Thanks for any help

You would need to use non-Reallusion motions if you are planning to sell, or otherwise distribute, motions with your custom characters. See here for using common motion types.


And check the EULA, of course.
https://www.reallusion.com/Content/EULA/EULA.htm

Thanks. The part I was missing was where the Mixamo motions were stored after importing. Using that motion file worked.