5th Ed SRD site
WARNING: This site has tons of 3rd party/Non-WotC material. This material is NOT legal for DDAL so please be careful what you choose from here.
Here is where you find "everything": the Player's Guide, the free Basic PHB and Basic DMG, Character sheets, etc.
DDAL Log Sheet Tutorial
The logsheets can be a little confusing, this page gives an excellent walkthrough of how DDAL wants them to be filled out for consistency.
5th Ed 'Sage Advice' Compendium
This is a PDF of all the Sage Advice answers in one place. It also contains links to the Basic rulebook PDFs and the errata for the core rule books.
A Great site for info
DDAL Frequently Asked Questions
The D&D Wiki page having official answers to the Frequently Asked Questions.