If you install mbed2.8.1 using the board manager of IDE1.8.19, it will be installed in the following directory This can also be used from IDE2.0.3.
\Arduino15\packages\Seeeduino\hardware\mbed\2.8.1
If you install mbed2.8.1 using the board manager of IDE1.8.19, it will be installed in the following directory This can also be used from IDE2.0.3.
\Arduino15\packages\Seeeduino\hardware\mbed\2.8.1