Radtest doesn't work with a clean install of Freeradius 4.0.0

[Shabda Raaj]

I have a clean install of freeradius (FreeRADIUS version 4.0.0 (git
#d9a670c)). I haven't changed any configuration files, the
installation was done by a git checkout and then building it on
Ubuntu.

I am trying radtest as described here:
https://github.com/FreeRADIUS/freeradius-server/blob/ce92146386b30bd7f9f57684666554154920acce/INSTALL.rst

radtest test test localhost 0 testing123

This gives me a radclient:: Unknown attribute "User-Name" requires a
hex string, not "test"

I tried a radtest 0x123 test localhost 0 testing123

Which gives me a
Unknown vendor name in attribute name "User-Name"