Connecting your LMN Account to your QBO Account is simple.
First, make sure you're logged into the LMN/QB Online Sync tool. You can use the Quickbooks menu in LMN and choose QB Online to get taken to the sync tool, or you can login directly using: https://accounting.golmn.com.
Once you've logged in, make sure you're on the Connection screen. You go there automatically after login or you can get there by clicking the Connect menu on the left side.
Next, click the big green Connect to Quickbooks button at the bottom of the screen. You'll be prompted to pick the company file you want to connect to.
Next, you'll be prompted to Authorize the connection. Click the Authorize button to give LMN permission to access your QBO Company information.
Next, you'll get a congratulations email showing you've successfully connected the two files. You can press the Close this Window button when finished.