I have searched in this community about how to bookmark on iPad Acrobat Reader Mobile, and I have discovered that this application have some free features and some suscription features. But, even if you have a monthly suscription you can't add, modify or delete bookmarks. Also, I have discovered that suscription iOS client have been complaining since 2016.
I would like to know how to make an official complaint to Adobe as a suscription client.
We apologize for the issue you are having trouble with. Adobe Acrobat Reader does have an option to create/edit/delete bookmarks. Please refer to this link for more information: Navigation. Also, please help us with the below-mentioned information to help you better,
1- Are you having this issue with a specific file or with all of them?
2- Are you logged in using a similar Adobe account with a subscription?
3- Kindy help us with the current version of your OS and Adobe Acrobat Mobile application.
If am not mistaken, the link refers to Acrobat for Android, the complaint is for bookmark for iOS.
Acrobat Reader for iOS or Android can't add/modify bookmarks in PDF files.