To install the addon: Fastest Bake

1. Open Blender.
2. Go to Edit > Preferences.
3. Click on the "Add-ons" tab.
4. Find addon file
5. Click on "Install..." 
6. It should then popped in the list of add-on tick the box, if not see step 7
7. Search for "Fastest Bake" in the search bar and enable the addon by ticking the box
8. The Fastest Bake panel should now be available in the Properties > Render tab>Fastest Bake
9. Select texture and click Bake .

You can now use the addon by selecting a texture and clicking the "Bake" button in the panel.

I hope this helps! Let me know if you have any further questions.