Step 1: Prepare your computer for connection
On your Chromebook, start by going here, the "Remote Support" section of Google's Remote Desktop web app. In the "Get Support" area, with the giant question mark, click the circular blue arrow, then click "Add to Chrome" in the box that appears and confirm you want to install the Chrome Remote Desktop companion extension. (If you don't see the blue arrow the extension is already installed and it should say "Generate Code")
Step 2: Give access for support
Go back to your original tab, and you'll find a prompt instructing you to click a "Generate Code" button in order to give someone else access. When you do that, the site will create a one-time access code that'll remain valid for only five minutes. Share that code to give access — on the phone, in an email or the Remind app.
You will then see a pop-up you will to manually click a button "Access" to approve the connection and then you'll be connected.