OK, Im not 100% sure, but my understanding of this is this:
You have your logger, which logs your data to its internal memory. You pay for the logger and thats it.
Now, if you want your data to be online and accessible from anywhere, Davis offers this possibility to have the logger send data to your WL site, which you automatically get with purchase. Then you pay some annual fee for the fact they offer you the space on their hosting and the data is available there. In addition the logger can also send data to WU.
2 problems:
1. you are limited to the very simple WL site, which does not show much info and in my opinion looks ugly and cannot be changed or customized in any way (as far as I know)
2. the logger cannot send data to any external FTP, which in my opinion is a rip off from Davis and basically forces you to use the WL site
Solutions:
1. use meteostick or meteobridge, which you plug in to the logger and then, send data anywhere you want - i.e. your own webpage, other weather networks, or even WU too, because the logger itself only allows sending at 15 minute intervals, with the other ones such as Meteobridge you can send as often as you like
2. use the logger to send data to WU and from there, have your own webpage, which would get data from there and do whatever you like with it
3. use the WL site, given you will have to pay the annual fee and be limited to what that offers