Manage Office 365 Calendar of Users in different Tenant using application permission

Question

Hi Everyone ,

I am faced with a particular problem , i want to access calendar of user's using application permission. My website will work same way like Calendly , i want the user to login using their Microsoft Business account (0ffice 365) and then give access to their Calendar , i have defined the Calendar.ReadWrite scope , this works fine . Presently i am able to access user calendar using delegate permission. What i want to do is access the user calendar using application permission . I have configured the Calendar.ReadWrite permission for application . I am able to access calendar of users in the same tenant where my application also resides using application permission , i am talking about external microsoft business account users who use my website and who have given me Calendar access permission.

I have tried using both AzureAD Multitenant and AzureADB2C Multitenant for applications , but somewhere i am missing something.
Let me know if anyone has faced this problem and solved it.

Thanks & Regards

Ritchie Fernandes