Hi - you are doing nothing wrong, except the package is out of date, so do not use it. We should take it down from the site to avoid confusion, but you may still find the documentation interesting...
However, there are lots of other options that are current.
Top of the list if you are using R is the abettor package, here:
https://github.com/phillc73/abettor
My favourite is the Perl package, here:
https://github.com/MyrddinWyllt/WWW-BetfairNG