If you have activated a pass it cannot be transferred to a different device by you.

You will need to contact customer services to have the pass disconnected from the current device before you are able to activate it on an new one.

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

It may take time before they are able to respond, it may not be possible before you are wishing to travel tomorrow morning.

Only Customer Support can help you with this if you already connected the pass to your app. Contact them through the form below and write your pass number and that you will start travelling tomorrow. 

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

@Nisar Ahmed Dear Nisar, thank you for your question! If you still need assistance on this matter, please send me a DM with your order number.

Kind regards,

Annie