I’ve tried with no success to run those examples given at the page. The error complaint as the log shows below
open source > level 1, order 1, name 'cont-yes.mkiv'
system >
system > ConTeXt ver: 2020.03.10 14:52 MKIV beta fmt: 2020.4.13 int: english/english
system >
system > 'cont-new.mkiv' loaded
open source > level 2, order 2, name '/Users/janneman/context-osx-64/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv'
system > beware: some patches loaded from cont-new.mkiv
close source > level 2, order 2, name '/Users/janneman/context-osx-64/tex/texmf-context/tex/context/base/mkiv/cont-new.mkiv'
system > files > jobname 'labels3', input './labels3', result 'labels3'
fonts > latin modern fonts are not preloaded
languages > language 'en' is active
system > synctex functionality is enabled, expect 5-10 pct runtime overhead!
open source > level 2, order 3, name './labels3.tex'
open source > level 3, order 4, name '/Users/janneman/context-osx-64/tex/texmf-context/tex/context/fonts/mkiv/type-imp-plex.mkiv'
open source > level 4, order 5, name '/Users/janneman/context-osx-64/tex/texmf-context/tex/context/fonts/mkiv/type-imp-texgyre.mkiv'
close source > level 4, order 5, name '/Users/janneman/context-osx-64/tex/texmf-context/tex/context/fonts/mkiv/type-imp-texgyre.mkiv'
close source > level 3, order 5, name '/Users/janneman/context-osx-64/tex/texmf-context/tex/context/fonts/mkiv/type-imp-plex.mkiv'
fonts > defining > font with asked name 'IBMPlexSans-regular' is not found using lookup 'file'
fonts > defining > unknown font 'IBMPlexSans-regular', loading aborted
fonts > defining > unable to define 'IBMPlexSans-regular' as 'ibmplex-11pt-ss-tf-0--0'
open source > level 3, order 6, name '/Users/janneman/context-osx-64/tex/texmf-context/tex/context/base/mkiv/meta-imp-dum.mkiv'
close source > level 3, order 6, name '/Users/janneman/context-osx-64/tex/texmf-context/tex/context/base/mkiv/meta-imp-dum.mkiv'
metapost > library 'dum' is loaded
metapost > initializing instance 'metafun:1' using format 'metafun' and method 'default'
metapost > loading 'metafun' as '/Users/janneman/context-osx-64/tex/texmf-context/metapost/context/base/mpiv/metafun.mpxl' using method 'default'
metapost > initializing number mode 'scaled'
metapost log >
metapost log > loading metafun, including plain.mp version 1.004 for metafun iv and xl
metapost log >
fonts > bodyfont '14pt' is defined (can better be done global)
fonts > bodyfont '16.8pt' is defined (can better be done global)
fonts > bodyfont '11.2pt' is defined (can better be done global)
fonts > defining > font with asked name 'IBMPlexSans-regular' is not found using lookup 'file'
fonts > defining > unknown font 'IBMPlexSans-regular', loading aborted
fonts > defining > unable to define 'IBMPlexSans-regular' as 'ibmplex-14pt-ss-tf-0--0'
lua error > lua error on line 70 in file ./labels3.tex:
function call [801]: ...-64/tex/texmf-context/tex/context/base/mkiv/node-syn.lua:435: attempt to index a nil value (upvalue 'filehandle')
60 \setlayer[BG][
61 preset=leftbottom,
62 hoffset=5mm,
63 voffset=3mm]{%
64 the context group}
65
66 \starttext
67 \startlines
68 \Name{Hans Hägar}
69 \Title{CEO · R&D}
70 >> \page
71
72 \Name{Wolf Schmidt}
73 \Title{0th Level Support}
74 \page
75
76 \Name{Mocca Bob}
77 \Title{the Builder}
78 \page
79
80 \Name{A. Rockefeller}