To unlock Acrobat's editing features in the mobile app, you need a paid subscription of Adobe Acrobat Pro DC.
If you do have a paid subscription of Adobe Acrobat Pro DC, then ensure that you're signed in in that mobile app with the AdobeID that is associated with your paid subscription.
If you're on an Android device you access the organize pages tool via the Thumbnails menu:
Hope you are doing well and sorry for the trouble. As described you want to rotate the page of the PDF file.
You can use the subscription-based organize tool to insert, extract, rotate, reorder, and/or remove pages from unshared files. Page level actions are blocked for shared and review files. To organize pages please check the steps shared in help ages listed below:
Note: These options are available with Acrobat premium services enabled.