Not sure what your are asking here but here is how you do it:
First on your PC move all your project folders to a disc formatted so it can be written from a PC and at least read from a MAC. Be sure to move/copy the WHOLE folder and not just the -cpr files. The folders will typically also contain settings and any audio files.
I would strongly advice to render all MIDI files to audio and do them both with and without any FX and then disconnect at least older fx and the instrument from the different MIDI tracks, thus you can have the “clean” MIDI files for further composition and/or instrument changes, the audio file for any fx changes or fx’ed audio files if no changes at all.
Then install Cubase for MAC on the new MAC. You also need to install all your 3. party instruments and/or FX that you may have on your PC. You cannot copy them from your PC. Both Cubase and all instruments/fx need a MAC installer that you most commonly may download for free from the websites respectively (given that you own the software). The only thing that might differ are instruments made to run under a sampler, like Kontakt. Here you can copy directly from your PC to you MAC. (And you may need to re-authorize - a lot). Any problems during installing will give you a clue if your projects contain something that won’t open on the MAC.
Then: Hook up the mentioned disc and find the project folders. Click on the .cpr file and it opens in Cubase for MAC. Really easy actually.
If you have not disconnected fx and/or instruments, and your old project contains anything that is obsolete in Cubase 8 or does not exist on the MAC under the new OS, any upgrade and/or platform change (even OS upgrades) might give you messages that Cubase does not recognize the settings. So I found it better to disconnect all instruments before saving the disc and rather reconnect after opening on the MAC.
Going from the PC platform to MAC has been real heaven to me. I am having no problems at all on my MAC. But I know people moving the other way with satisfaction too. I do however occasionally miss some VST instruments that are not on the MAC platform.