Stuck at 99% for an update....
A person on the Mac forums had this issue and he said “changing the language in the top right corner caused the whole patch to re-download and complete” he did note that Spanish did not work, but FRENCH did. Once it finishes downloading, you can change the language back to your default. (the devs recommend leaving the client run 10-20 minutes to re-initialize an alternate download, but some peeps have reported it can take up to overnight plus a few more hours on top of that)
This may or may not work for you, but several peeps have reported German to work also.
Please post back and let me know if this works for you.