Hi nithu m,
Thank you for posting your query on Microsoft Q&A!
Can you confirm if you have an Exchange Online license? As this would generally be required for the service to show up under "APIs My Organization uses"
Regarding the trial, you will need to confirm a payment method before you can activate the trial, even if it is not used.
Let me know if this does not help and we can take another look.
Please "Accept the answer" if the information helped you. This will help us and others in the community as well.
Kind Regards,
Donal