If your using Debian Debian 9 (“stretch”), and the Sipeed USB-JTAG/TTL RISC-V Debugger, you will need to install the libusb, libftdi, libftdi1, and some other libs… maybe. If they are not installed you get a message about missing libs.
As “Visual Studio Code” with the “platformIO” plugging will not install them.
Also you will have a problem with libmpfr.so.6 not been present on Debian 9,
the way around this is to soft link libmpfr.so.6 to libmpfr.so (assuming a 64bit system)
sudo su; cd /usr/lib/x86_64-linux-gnu; ln -s libmpfr.so libmpfr.so.6