I have to correct this. There is no RS485 inside the BMS. It's a TTL signal coming from the one of the micro controller UARTs. RS485 uses three pins:A, B and GND. A and B are a balanced, differential signal whereas TTL uses Rx/Tx lines and GND. Rx and Tx are receive/transmit lines and are independent, non-differential and more akin to RS-232.
Thus, the converter that they sell turns the TTL signal from the UART into an actual A/B RS-485 signal (the module contains a microcontroller etc. to do this). Then, you typically connect a RS-485 to USB converter (which turns this into a kind of RS-232 again, simplified). It's therefor much easier to just take the existing TTL signal from the UART and convert that with a TTL to USB converter.
I don't believe (unless I miss a version) that any of the BMS has RS-485 by default even through that's what
@Nami indicates in the pictures of the BMS. In reality, this is a misnomer: it should be TTL, which can be converted to RS-485, but which would be easier for us if they would just provide a TTL to USB converter that plugs in there instead of going TTL -> RS485 -> TTL -> USB...