If your store isn't hosted on the root domain then you'll need to also include the path it's on. For example, if it's accessed via https://example.com/wp instead of https://example.com then you'll need to enter for the Host field:

Another thing to check is to ensure permalinks is enabled. To do this, navigate to Settings > Permalinks on the left sidebar. Note that these are WordPress settings, not WooCommerce settings!

Then ensure that any option other than Plain is selected:

Finish by saving your changes.

After that, you should be able to connect your WooCommerce site as a sales channel within Trunk.