Help

[Zipper]

Hello. My father is a coder since probably when I was born (2007) and I have asked him to buy me a new gaming PC as my old crap doesn't even run CS Go properly. He challenged me to use my wisdom to earn it. He set a password to 3 .rar files, where he left me a message. If I unlock it and read it - he will purchase me a brand-new PC.
The first hint was easy - he named one rar file R2ludGFyZQ== it appears my mother's name in B64. This was a password to open it. There I found a Text file with @743C23F27F54377661299758A56CT494@ in it and a text saying that it would help me to understand the next step. I have no idea about the @@ as the rest of the string appears to be a HEX string, but why it is incorporated in the @? I have read so many articles online but found nothing to hook on. It should be something simple, but clearly out of my knowledge. Could you guys help me to figure out what this could mean?

 

[VBService]

Did you tried in that way.
Char "@" in hex is 40 or "at" in hex "a" is 61, "t" is 74

hex​	string (possible password)​
"@743C23F27F54377661299758A56CT494@"​	"CÂ?'õCwfuVI"​
"@743C23F27F54377661299758A56CT494"​	"CÂ?'õCwfuVI"​
"743C23F27F54377661299758A56CT494"​	"t<#òT7va)X¥l"​
"743C23F27F54377661299758A56C94"​	"t<#òT7va)X¥l"​
"40" + "743C23F27F54377661299758A56CT494" + "40"​	"@t<#òT7va)X¥l@"​
"6174" + "743C23F27F54377661299758A56CT494" + "6174"​	"att<#òT7va)X¥lat"​

view from console

[ code on-line ]

console.clear();
const htos = (hex) => hex.match(/.{1,2}/g).reduce((a, c) => a + String.fromCharCode(parseInt(c, 16)), '');
 
console.log(htos('@743C23F27F54377661299758A56CT494@'));
console.log(htos('@743C23F27F54377661299758A56CT494'));
console.log(htos('743C23F27F54377661299758A56CT494'));
console.log(htos('743C23F27F54377661299758A56C94')); // without T4 invalid hex code
console.log(htos('40' + '743C23F27F54377661299758A56CT494' + '40'));
console.log(htos('6174' + '743C23F27F54377661299758A56CT494' + '6174'));