To install liveries for the TFDi Design MD-11 in MSFS please follow the steps below;
For this example, we will use the Lufthansa Cargo GE livery D-ALCM.
1) Go to https://tfdidesign.com/store/download/category/14/TFDi-Design-MD-11.html and choose MSFS:
2) Click on the livery you wish to download:
3) Once the livery has been downloaded extract it from the RAR file:

4) Place the extracted folder into your MSFS "Community Folder":

5) Ensure the naming structure is as shown:
6) When you have loaded MSFS please select the correct version of the MD-11, in this case, the MD-11F with GE engines:

7) Using the LIVERIES tab you will now be able to see the installed livery:

