The references in the Release notes to a new Akamai based installer apply to the PC client only.
The Mac Client download downloads the file: LOTRO_MAC_4.46.pgk
This is the Happy Cloud installer, however it does use Akamai apparently as its data source.
It does appear that the Happy Cloud installer has been updated. As it claims that it now needs 20.3 GB of space (which is correct for 12.2).
** First update ***
First attempt - HC downloads in approximately 10 minutes to the point where the "Game is ready to play" slider is full green.
At that point, you can (auto)Launch the client. ... and, sigh, it will spend about 20 minutes patching!
Then when you log in, if you launch a (I suspect below) level 20 character you can begin playing -- i.e. any character who is in the "Introduction" or "Starter areas."
Should you select and try to play a character who is in an area beyond that point, you will need to wait until that area is downloaded, before you can get "in-game.
In my "test case" I selected a level 65 in Thror's Comb in Enedwaith -- and I had to wait about another 10 minutes (on my 20 meg Cable modem) for it to load.
* File downloaded: LOTRO_MAC_4.46.pgk -- this is the Happy Cloud installer, not Akamai, but uses the Akamai network for data transfer
* Double-clicking on the .pkg file Requires Gatekeeper access:
- Open System Prefrerences
- Open Security & Pricacy
- Note the message: "LOTRO_MAC_4.46.pkg" was blocked from opening because it is not from an identified developer
- Click "Open Anyway"
- installation will begin
At this point, you can select a destination disk driver for the 20.3 MB install.
I have not yet done any other significant exploration/verification of this new mechanism (or the client itself) yet.