Can i use my Serial number (purchased for PC) for the Mac version of the game?

Here is your answer : YES  https://help.ea.com/article/simcity-for-apple-mac-faq

5. Does SimCity support cross-platform play between PC and Mac users?
Yes. Everyone is playing together on the same servers. That means PC and Mac users will be building cities alongside each other.
 

6. If I have both a PC and a Mac, do I have to purchase two copies of the game if I want to play on both systems?
All players who registered their copy of SimCity will have access to both the PC and Mac versions of the game through Origin. Only one Origin account can be logged in at a time. No additional purchases are necessary.
 

7. If I previously purchased a copy of SimCity for PC, do I need to purchase a copy for Mac, too?
All players who previously purchased a copy of SimCity for PC will find the Mac version already pre-entitled in their Origin accounts in August. No additional purchase is necessary.

Hope this helps
---------------------------------------------------------------------------------------｡ Cheers ｡-----------------------------------------------------------------------------------------
► ✔ Please don't forget to resolve your question if this helps as it could help others &all . Click XP if someone helped! ◄

***Please note...I do not work for EA/Origin. Questions belong in the forums,Solution is like medicine,same medicine/solution may not work on same problem

I don't answer questions via PM.  AHQ is "Player-to-Player" technical self-help forum

its for the Sims 3 and i could not find the link in the origin store ☹️ 

any particualr place i should look?

thanks for the quick response 🙂

thank you did not know about registering