You should be able to find these digital assets on the “Digital Content” section of your account. This section is under the “My Account” heading in the top right of the site. All of the downloads available to you will be listed there. 
Click the title of the asset you would like to download and you should see a note that the item is being personalized and to click again in about 60 seconds. The second click should display that the asset is ready for downloading. A third click should begin the download of the asset. 
The “Trouble Downloading this file? Click here” link should only be pressed if you get an error message when trying to download the file. 
If you have a large amount of digital content, you can use Ctrl+F or Command+F to open the find command to search your downloads page for a specific product.
If you encounter any difficulties, we have provided a comprehensive guide to help our customers obtain their Humble Bundle downloads: https://paizo.com/threads/rzs42hdn?Using-Partner-Redemptions-to-access-Digital