If you just want the of advice for keeping Eaglercraft up to date from a drive source:

Navigate to your "Eaglercraft Upd" folder. Click the HTML file once.

"UPD" is shorthand for Update or Upload within the community. Unlike the official Minecraft launcher, Eaglercraft does not auto-update. Because the game relies on a single HTML file (or a ZIP file containing assets), developers release new "patches" to fix:

From community posts (Reddit, Discord, GitHub):

In response, the community shifted toward decentralized distribution. The "Drive Update" method emerged as a primary way to bypass filters: