net10 international calling

I bought net10 sim cards here in the US to use with my German phones. Everything is working right now, and I want to add the international calling plan. This process seems fairly easy, but to directly call any numbers, I'd need the net10 apk for international calls which I cannot get because my google account isn't yet set to US, as I still have a 12€ value on my German address.
Is there a way of getting the international calling apk? I've used google, but all links I find redirect me to google play sooner or later which won't let me install the app due to regional restrictions.

Thanks for any advise.