The files should be run in the order indicated by the file names.
If you source the make_codebook.R file, you should then be able to call the objects cb_dat_main_long and cb_complete_table.
These objects have the same names as the columns in dat_main_long and complete_table but contain a sort description of the respective variable.
The vroom package which is used to read in the data gets tripped up by double quotes followed by a comma in the data.
Otree saves the list of pages as "[""Page1"", ""Page2""]" with the double quotes indicating a single quote that should not end the string.
While this usually works fine for vroom for some reason it interprets the double quotes as end of string if it is followed by a comma.
I therefore manually removed these characters as I don't need that list anyway.