Hello,
The sequence summarized by #BoMo6194 (thank you) was a success. I just added a restart PC before (re)installing Xbox app. I finally got the download page (45.86 GB). More than a week for reinstalling MSFS !!!
However the success is not complete as now only 2 planes are available. I read it was a consequence of an installation not on the C:\ drive. The modification of UserCfg.opt is not a solution : all is to be downloaded again. In the “content manager” panel others planes are not proposed for downloading.
Aircraft’s folders in Official\OneStore contain the missing planes excepted one, the C172SP-classic (there is the G1000).
I am sure there is a solution as after the initial installation on D:\ all planes of the premium deluxe version were available.
Since the beginning each update of the sim is a nightmare. To be positive let’s say it is a good way to learn what is inside a box which would have to be only a black box for most simmers.
Best regards