Follow my screenshot below to configure your account. Remember change the mail address to yours.

If you have set two-step-verification on your Google account, the normal way that introduced in other guide may not work.

Here is the solution:
1. Visit and login your Google account: https://myaccount.google.com/

2. Find "Signing in to Google" in "Sign-in & Security" section:


3. Click "App Passwords":


4. Choose "Mail" for the first drop-down menu, and Choose "Other" for the second one:


5. Then type the name you want in the emerged input box.

6. Click "generate" button, and a window will be popped up. Read the "How to use it" carefully for your account's safe.

7. Copy the 16-character password for next step:

Type directly the 16-digit-password generated from your Google account to the password input box in the SAO Mailbox configuration window.

Then click TEST. Hopefully, it will work.

Have fun!