Dear Team,

I have Banana Pi R4 board, it is possible to install Mikrotik Router OS there ? if it's possible what is the step to do? Please Guide me the same.

Nope, not possible.

Only Mikrotik HW, x86 or virtual machine.
See here:
https://mikrotik.com/software

Yup. Even when software for Ampere (ARM-based general purpose machines) becomes available it almost definitely won't allow running on 3rd party ARM-based hardware (Banana Pi R4 falls into this category) because it'll lack most of needed drivers for peripheral hardware (switch chip, SPI flash, etc.).

I think you should look at OpenWRT instead.
I don't know if it support your specific card.

https://openwrt.org/toh/sinovoip/start

Or get one of those "software router" x86 boxes at Aliexpress that have a couple of ethernet ports.
You can get the minimal options for memory and storage, and that makes them quite cheap.