In my attempt to replicate the issue, everything appears to function correctly on my testing site. The order completion email I received displays the products and the download link in color, with an underline.
However, the issue you’re experiencing with underlined and coloured hyperlinks not showing in your order completion emails could be due to a few reasons.
It could be related to your email client’s settings, which may be overriding the HTML styles in your WooCommerce emails. Alternatively, it could be due to a conflict with your theme or another plugin.
To troubleshoot this issue, you could try the following steps:
Check your email client’s settings to ensure that it’s not set to display emails in plain text.
Temporarily switch to a default WordPress theme like Storefront and disable all plugins except WooCommerce to see if the issue persists. If the issue is resolved, you can reactivate your theme and plugins one by one to identify the source of the conflict.
If the issue persists after trying these steps, please share a copy of the following:
System Status Report: Navigate to WooCommerce → Status. Select Get System Report and then Download for Support.
Fatal Error log: Share a copy of any fatal error log found under WooCommerce → Status → Logs.
You could copy and paste your reply or share it via Mozilla Community Pastebin and share the link here. This will help us investigate further and provide you with a more accurate solution.