Type TOPL in the command line or click on the button at the Add-ins tab ribbon to start the command. Select the texts and Mtexts to rotate and press enter (a selection filter ensures that only texts and Mtexts are chosen). Follow the instructions and option in the command line:

Specify rotation angle or [Polyline]

Type the rotation angle to apply to all texts, or type P to select a polyline and press enter.

Specify rotation mode: [Readable/Align]:

After selecting the polyline, choose the rotation mode: type R to make the objects readable or A to align the objects to the nearest point on the polyline.

Specify base point: [Center/Insertion]:

Lastly, specify the base point: type C to rotate around the object's center or I to rotate around the insertion point.

Press Enter, and you're done! The objects will rotate according to your settings.

The installer that was run when you downloaded this app/plugin from the Autodesk App Store will start installing the app/plugin. OR, simply double-click the downloaded installer to install the app/plugin. You may need to restart your Autodesk product to activate the app/plugin. To uninstall this plugin, exit the Autodesk product if you are currently running it, simply rerun the installer and select the "Uninstall" button. OR click Control Panel > Programs > Programs and Features (Windows 7/8.1/10/11) and uninstall as you would any other system application.