[Koha] bogged down in a koha install

[o1bigtenor]

Greetings

Following the 'destructions' at:
https://wiki.koha-community.org/wiki/Debian#Before_you_begin

have worked my way through until trying to set up plask

$ sudo a2enmod headers proxy_http

then:

$ sudo koha-plack --enable libraryname

# a2enmod proxy_http
Considering dependency proxy for proxy_http:
Enabling module proxy.
Enabling module proxy_http.
To activate the new configuration, you need to run:
  service apache2 restart
root at memyself:/# service apache2 restart
[ ok ] Restarting Apache httpd web server: apache2.
root at memyself:/# koha-plack --enable library
[FAIL] Error: Invalid instance name library: failed!

# dpkg -l | grep plack
ii  libplack-middleware-logwarn-perl       0.001002-1
             all          converts warnings to log messages
ii  libplack-middleware-reverseproxy-perl  0.16-1
             all          module supporting apps to run as a reverse
proxy backend
ii  libplack-perl                          1.0047-1
             all          interface between web servers and Perl web
applications

so - - - I think I do have plack - - - - not sure how to get whatever
needs to see libplack-perl looking in the right direction.

(perl is already the newest version (5.28.1-6+deb10u1). - - - - if it matters.)

TIA

(just subscribed to the user list and haven't seen any questions on
install so chose to cc the dev list - - - hopefully not deprecated
behavior - - - - :-)  !)