Your RAM amount is enough for the game but if you have something like a webbrowser running in front you can have this kind of issues, you can enable the texture streaming mode in the graphics settings it helps with low memory also please make sure that you close softwares like web browsers that eat a lot of RAM, i'm nearly sure that it's an out of memory issue (You crash because you reach the openworld that require more memory to run, it use ~4GB of memory but OS can take up to 2GB and webbrowser too so it can quickly overrun your memory)
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