Here’s the original Rokoko tutorial. But it does not work: https://www.youtube.com/watch?v=vRDJ7vAYll4&feature=emb_title
The problem: once it is time to copy the imported animation track to the correct new character’s track in the dope sheet, you cannot simply copy and paste. If you do, the entire imported character’s motion data will be (incorrectly, jumbled) copied to the new character’s tracks.
If you select individual keyframes from the imported motion track, you CAN paste those into the new character’s tracks. However, it’s a nightmare having to click/shift-click on so many things.