Hi bobandted and welcome to the forum!
First of all, thank you for your purchase. I am using AmiKit here on Big Sur so that is not a problem for sure.
Please make sure none of your Mac drives are named SYS. Otherwise AmiKit might get confused as in Amiga world this is an alias for boot drive.
Or perhaps, before you start AmiKit, in WinUAE CD/HardDrives section turn off the following options: "Add PC drives at startup", "Include removable drives" and "include network drives".
Hope it helps? Please let me know.
Btw. I recommend installing AmiKit with Amiga Forever rather than OS4.1CD which contains older OS3.1.