I was told that there are versions of this game from RC1 to RC7. Where can I access each version and where can I check it?

as you can see in resources, there is a link for full screen game that we normaly use in runs: https://www.google.com/logos/2020/kitsune/rc7/kitsune20.html well, see in a part of the link how is written "rc7"; well that part of the link is to decide the version, in the same link you can manualy change the number for the version you want, as easy as that btw recommended to use rc5 for old version ones

RC1-RC6 are generally the same version of the game (bug fixes etc, as KilleDragon said best option is RC5). RC7 is content update that includes new quest new sports. Check guide for more. And as Killedragoin said everything is accessible in resources.