Using wrong base and adding more wrong is a poor excuse.
Yes, the guide can be easily fixed: it should be replaced with a link to https://github.com/OpenRCT2/OpenRCT2#linux-1 which covers everything you tried explaining, but got wrong.
Which part of
DESTDIR=. make install # the install target creates all the necessary files in places we expect them
That you linked to, do you not understand?