Enter your printer's address - its IP (shown on the printer's idle screen) or tinymaker.local - and press Save. Chrome asks to let the extension read that one address: Allow.
Pin it so the icon stays on the toolbar: the puzzle icon at the top right, then the pin next to TinyMaker status.
Good to know
It only reads the printer's status, about once a minute - it never changes anything. No account, no tracking: privacy policy.
Had the earlier zip installed by hand? Remove it in chrome://extensions first, otherwise you get two icons. The manual zip install is gone.
For the first months Chrome may call it not trusted by Enhanced Safe Browsing. Every new developer starts like that, and it clears on its own.