Good evening everyone
I know that the topic has been raised dozens of times but I wanted to share my experience and of the solution that I found was my problem.
I have had several problems to install the add-on liveries for the PMDG 747.
In reading (sorry, I don't remember on what forum, can be by watching a video on Youtube) that he had to go on the site of PMDG, press the delivered desired and click on "run". And it works beautifully.
I'll try taking a delivery from AVSIM and i will keep you informed.
If i can help someone, don't hesitate to contact me.
Happy New year to all.
King regards
Eric Koch