Can’t install OS X on mac book pro. Pls Help!

I am from Germany and currently in Canada. I just got my moms old Mac book pro and deleted all her data as suggested on the Apple website. When I want to install OS X and log in with my German Apple ID, it says that I will be transferred to the German App Store. But when I type in my information, it says that there is no app available at the moment and I should try again later. How can I get my Mac running.