Could you move and activate your pass on your new phone?

The contents of your trip cannot be moved as far as I know (that data is physically on your old phone). But you can just add your journeys on your new phone before you board a train.

The problem is that I still couldn’t activate it on my new cellphone.

In that case, contact customer service:

https://eurail.zendesk.com/hc/en-001/requests/new

Include your pass number (from the confirmation mail or your Eurail account) and mention you're currently travelling.

Also describe what happens when you try to activate it on your new phone and include screenshots of any error messages.

Also check your device settings:

https://eurail.zendesk.com/hc/en-001/articles/7560433913245-What-should-my-device-settings-be-to-run-the-App-

Have you followed the instructions for how to move your pass to the new phone?

https://www.eurail.com/en/eurail-passes/eurail-mobile-pass/mobile-pass-faq/what-should-i-do-if-i-lose-my-phone

Thanks to all good advices, I finally got this problem solved through the help from their customer service team, they found my problem and removed the link with my old phone then I can add the pass in my new cellphone smoothly.