LaTeX Error: Environment longtable undefined

[kript]

I am no LaTeX expert, but happy to work with someone to get this sorted out?

Failed to build the handbook. the first make install hung. Removed the /dev/null redirection and ran with handbook/src$ pdflatex --output-dir=build/tex/ build/tex/main.tex

Ubuntu 20.04.2 LTS
pandoc version 2.5-3build2
texlive-latex-base 2019.20200218-1
build-essential 12.8ubuntu1.1

Error is;

(/usr/share/texlive/texmf-dist/tex/latex/pdfpages/pppdftex.def))

Class scrbook Warning: Usage of package `tocloft' together
(scrbook)              with a KOMA-Script class is not recommended.
(scrbook)              I'd suggest to use options like `listof=entryprefix',
(scrbook)              commands like `\listoflofentryname' or
(scrbook)              `\listoflotentryname', and `\DeclareTOCStyleEntry' or
(scrbook)              `\RedeclareSectionCommand' instead of this package,
(scrbook)              because it breaks several KOMA-Script features of
(scrbook)              the list of figures, list of tables and table of
(scrbook)              contents, i.e., options like `listof=numbered',
(scrbook)              `listof=flat or `toc=flat', commands like
(scrbook)              `\BeforeTOCHead{...}' and `\AfterTOCHead{...}',
(scrbook)              `\BeforeStartingTOC{...}' and \AfterStartingTOC{...}',
(scrbook)              all features of `\DeclareTOCStyleEntry',
(scrbook)              and the ToC entry features of `\DeclareSecionCommand'
(scrbook)              and `\RedeclareSectionCommand' of levels
(scrbook)              `part', `section', `subsection',
(scrbook)              `subsubsection', `paragraph' and `subparagraph'.
(scrbook)              Nevertheless, using requested
(scrbook)              package `tocloft' on input line 14.

(/usr/share/texlive/texmf-dist/tex/latex/tocloft/tocloft.sty)
(/usr/share/texlive/texmf-dist/tex/latex/upquote/upquote.sty
(/usr/share/texlive/texmf-dist/tex/latex/base/textcomp.sty))
(/usr/share/texlive/texmf-dist/tex/latex/l3backend/l3backend-pdfmode.def)

LaTeX Warning: Unused global option(s):
    [oribibl].

(build/tex//main.aux)
Runaway argument?
{\contentsline {subsection}{\numberline {1.6.2}Bef 
! File ended while scanning use of \@writefile.
<inserted text> 
                \par 
l.25 \begin{document}
                     
? 

[kript]

Incorporating the fixes from #142 gets it to build further but then gives a lot of errors similar to;

LaTeX Warning: Float too large for page by 77.36844pt on input line 109.

) [331 <./chapter_13_secure_file_sharing/onionshare_6.png>] [332 <./chapter_13_
secure_file_sharing/onionshare_7.png>]
chapter 15.
(build/tex/chapter_14_appendices/contributions.md.tex

! Package inputenc Error: Unicode character ́ (U+0301)
(inputenc)                not set up for use with LaTeX.