Click “Load unpacked” and choose the folder
With Developer mode on, three buttons appear top left. Click Load unpacked. A file window opens.
Go to where you put revodics-extension, click that folder once so it is highlighted, then click Select Folder. Pick the folder itself, don't go inside it.
Revodics now shows up as a card on the page, with its switch on.
Chrome says “Manifest file is missing or unreadable”?You picked a folder one level too high or too low. Choose the folder that has manifest.json directly inside it. That is revodics-extension.