The Texture tool will show up in Illustrator’s main toolbar (which must be in Advanced mode: View > Toolbars > Advanced
). Stacked under this is the Texture Brush Tool.
Texture and Texture Brush Tool in the Advanced Toolbar
The Opacity Brush Tool will show up in Illustrator’s main toolbar (which must be in Advanced mode: View > Toolbars > Advanced
).
Opacity Brush Tool location in the Advanced Toolbar
The panels will automatically appear when a tool is activated, or you can find them under the menu item Window > Astute Graphics > ...
and clicking inside the panel with activate the tool.