your search-fu is weak... but anyway :
To access Lamannia ( I'll refer to is as L-Space after ) you need to download the L-Space specific client.
Check this pinned thread for more information :
https://www.ddo.com/forums/showthrea...ccess-Lamannia
The client can be downloaded by clicking in the first link of the post.
And to answer the most obvious question : No, it is not going to erase your DDO game directory... it installs itself in another one.
For the rest, check the Test Dojo ( you can't miss it ) :
https://www.ddo.com/forums/showthrea...jo-on-Lamannia
and if you want Turbine Points to buy stuff from the L-Space store you cna talk to Sir Poincelot, IIRC he decided to move from his long lasting location and he is not a Test Dojo Resident :
https://www.ddo.com/forums/showthrea...Lord-Poincelot
( first post has been updated with his new location, so he is in The Dojo. )