Gta 5 online when do I get Twitch prime benefits?

I made twitch Prime to get the kostaka u-boot in gta 5 online. In the game, I've already received twice the weekly $ 200,000 that you get as a twitch prime user. But I still haven't got the kostaka. It's been 11 days since I did twitch prime. How does it work, did I do something wrong? Will it be so that I can then buy the submarine for $ 0 or how does it work?

You don't get the Kosatka, you only get the sonar for free.

Thanks ^^