Update samsung s6 edge plus outside US?

Hello, a couple of years ago I bought an unlocked Samsung S6 edge plus in Walmart, for reasons of my work I moved to South America and since then I have tried to update my phone without any success. Is there any way to update the device? I do not have any of the security updates that leave me with a very vulnerable phone.

BUILD VERSION : G928AUCU1AOGG

I would really appreciate if someone could help me. Thanks.