There is no such thing as a dll injector for macOS because macOS doesn't use dll files. Learn dylib injection or, better yet, learn Frida. Save yourself the headache and the malware.
lldb -p <TargetPID> (lldb) expr (void*)dlopen("/path/to/test.dylib", 0x2) dll injector for mac
A DLL injector running in a VM injects into the VM’s virtual processes , not the macOS host processes. You cannot inject a DLL into Finder.app from inside Parallels. There is no such thing as a dll