Yes, build-in Serial terminal is currently supported only for boards what have already updated DAP Link firmware (For example FRDM-K66F I think). I believe this will be supported for more boards in the future. But you can use any other Serial terminal pc app like you use it until now.
The printf function is working normal, but it does not print out any flouts because that is new default settings what can be changed, please look - Minimal printf and snprintf.
The library is currently unavailable because of reported Mercurical issue, however I know this library and how I wrote you above, that is not related to KSC, it is related to MbedOS version.
You probably use an old MbedOS version (definitely older than MbedOS6+), that is why you have problem with everything.
MbedOS versions
- MbedOS 2 - odest from 2010 and marked as deprecate maybe more than 3 years ago
- MbedOS 5 - First release in 2016 and latest version is MbedOS 5.15.9
- MbedOS 6 - First release in 2020 and latest version is MbedOS 6.16
KSC supporting whole MbedOS6+, MbedOS 5.12+ and a version of MbedOS 2, but recommended is latest one, the latest is Mbed OS6.16.
All old libraries were made for MbedOS 2, some of them are working also with MbedOS 5, but most of them are not compatible with MbedOS 6+. Libraries are not in Mbed responsibility, it is community part of job, but people are lazy.
Do you have a list of libraries or already prepered old programs what you use for your class?
BR, Jan