Hello Ashish,
I hope you are doing well. I am sorry for your experience with the Acrobat Premium subscription.
Since this is a mobile-based subscription, I suggest you contact support for Google Play Store, and they would be able to assist you with the refund procedure.
To know more, please refer to the link: Subscription Services — Acrobat for Android Help (adobe.com)
To go forward with the refund process, you can visit the below Google Play Store link:
Request a refund on Google Play - Google Play Help
Let me know if it helps.
Thanks,
Souvik.