Here is my British Airways livery (G-XDHX) for the PMDG 737 im MSFS2020.
PMDG products use The PMDG Operations Center (OC2).
1. Extract the PTP file from the downloaded zip file.
2. Place it anywhere your PC (typically the downloads folder). DO NOT place it in the MSFS folder structure, including the Community folder
3. Open the PMDG Operations Center and Follow these steps when Ops Center is open.
1. Click the Aircraft and Liveries menu
Choose Livery Utilities
2. Select the Simulator,Select the Product,Select the Variant
3. Click Install from PTP file
4. After the Open window opens, navigate to the folder you saved/extracted the PTP file to
5. Click Open and your Done
NOTE: I will not support this as a “Drag and Drop” livery. Please put a link to the livery if using it when creating content such as streaming or youtube. Thanks