How do I install GTA 5 on my second PC?

Beautiful good day,

I would like to install GTA 5 on my PC. But I already installed it on my laptop. Important I bought it as an online code if that matters and I do not have it on Steam. I thought I could easily download it from Rockstar but they want to buy it again. Could someone please help me. Mfg Anna

You can download the GTA 5 client as often as you like on other PCs.
The download is quite hidden on the Rockstar site.