There is no major change between the versions of the Exporter.
Although the latest one is recommended for the current Octane versions even the older one should work.
Your ../Plugins/Octane/ folder should also contain the older file "Octane_1022.rb" as well as the newer one "Octane/Octane_1024.rb" [I can't see in your screen-shot as the window is scrolled down]. If not install the _1022 version then the _1024 version over it - then you will have both .rb files.
The file inside ../Plugins/ called "Octane_loader.rb" loads a particular version.
To load the latest version it says
#load "Octane/Octane_1022.rb"
load "Octane/Octane_1024.rb"
with the earlier version disabled by the leading '#'.
To let the older version load you swap the '#' thus
load "Octane/Octane_1022.rb"
#load "Octane/Octane_1024.rb"
Now _1022 will load/run after a restart.
If you now get that to open OK then something in the newer version of the rb file is incorrect - although I can't see what it might be
If it still fails you can try reinstalling _1022 and overwriting all files - that version will now load/run on a restart.
If it opens OK then the error is in the newer versions of the dialog's file [html/js/css etc] - although again I can't see what it might be
At least we then have clues about from where the error is emanating...
Let me know the outcome...
The question about 'which web-browser' is because Sketchup's web-dialogs use each system's web-browser to make themselves with html files - so it might be possible to have the system settings conflicting with these html file's coding etc - it may be I can force something in the dialog's html to override that...
E.G. <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> works for me but perhaps not for you ?
I need to get feedback on what is failing first though...