Here are the required specs for Baldur's Gate 3:
CPU: Intel i5-4690 / AMD FX 4350
RAM: 8 GB
OS: Windows 10 64-bit
VIDEO CARD: Nvidia GTX 780 / AMD Radeon R9 280X
PIXEL SHADER: 5.0
VERTEX SHADER: 5.0
FREE DISK SPACE: 150 GB
DEDICATED VIDEO RAM: 3072 MB
Baldur's gate is taking up 5+ gigs of memory on my PC...pretty much guaranteed you will need to shut down as much stuff as you can to play (especially browsers, Chrome is eating 6GB on my machine because I have a bunch of tabs open). If you use more memory than you have, it tries to use your hard drive as memory (which is incredibly slower). 8GB of memory is pretty rough nowadays.
Your CPU is a 2 core CPU and is well under an i5-4690. You can try to close down as much stuff as possible to reduce the load on it. Outside of that, there's no getting around how underpowered it is.
Your GPU is under the required spec...need at least a 280X with 4GB of memory (I doubt your 270 has 4GB of memory).
If you want to play, I would recommend the best CPU your motherboard can handle and a used RX470/RX480/RX570/RX580 off Ebay. You might also consider getting a full 16GB of DDR3 to make your life easier.
If you don't have money for some replacement parts, I would say you need to get a refund.
