Tiles@home must be started manually AND you need to request a username/password in order to be able to get render requests and upload the results.

There is a section in the T@H Install guide about passwords.

Because Tiles@home does not use an encrypted or otherwise signed method for preventing users to upload crappy tiles, therefore most T@H users are well know users of the project (which can be considered thrustworthy). So you might find your password request denied, dunno actually.

Note: Tiles@home has way more CPU power (i.e. lots of contributors) at it’s disposal than the servers at OSM can handle, so you’ll find that your client is mostly doing nothing…