If you multiply seconds by 60 you don’t get RPM. See below for proper computation.

if you could help me it would be amazing

Try this:

The LabVIEW example linked below shows how to do that, and how to convert Counter.get to RPM:

You need to know the cycles per rev per channel for your encoder. Use that value instead of “99” in the above LabVIEW example.

Use your desired FPGA sample averaging value instead of “5”.