Connecting your Merchant account to Google Adwords is very easy and can be done in less than 5 minutes.
1 ) Login to your Google Merchant account
2) Go to Settings > Adwords
3) If your Google Adwords account is on the same account as your Merchant email address, than you can click on the Link button (circled in the image below).
If your using a different email addresses you can click on Create Account
Do not ‘Create Shopping Campaign’ inside Google Merchant, sources have suggested that this could lead to a suspension. Instead go to Google Adwords.
When logged in, create your Shopping Campaign there.