The easiest way is to import the players using a text file. You can import historical players one by one or by using a text file. I have not done this in a while. Probably back in 2019 or 2018. I posted an example of the text file I used. You need to go back to posts from those games. Search on "import historical player".
This post may help.
https://forums.ootpdevelopments.com/...torical+player
From the manual.
http://manuals.ootpdevelopments.com/...orical_players
Just save the text file, unlike me.