Thanks for the quick reply !
You put me on the right track to solve my problem . Long story short : I updated my old obsolete Anki web on my former Mac and it was almost working except that it was full of bug messages like : ID or password was incorrect please try again or syncing… it was frozen up … So I decided to send this defective updated Anki version via airdrop on my new Mac and it almost worked . The system requested a V3 scheduler instead of V1 and after updating , everything works perfectly on my new Mac !!! I understand nothing and for me it’s like magic ? Anyway my problem is solved , this is a real lesson to me : in the future I will keep everything up to date to avoid stressfull disapointment !