One of the requirements to set up Google Shopping is having your Merchant Center and Google Ads accounts linked.
When you approve a link between your Google Ads and Merchant Center accounts, you'll allow your product data to flow from Merchant Center to Google Ads for use in advertising campaigns.
Only a Merchant Center account user can request to link the accounts.
Once the Google Ads account owner approves the request, some information is shared between accounts.
Google Ads account owners and either admin or standard Merchant Center users can remove the link at any time.
If you remove the account link, Shopping campaigns that rely on product data from this Merchant Center account will stop serving ads.
You’ll need to have admin access to your Google Ads account to link Google Ads and Merchant Center accounts.
Request link to Google Ads in Merchant Center
Before you start, be aware of your Google Ads ID. It's the 10-digit number in the top right corner of Google Ads (xxx-xxx-xxxx).
In your Merchant Center account, click the tools icon, then click Linked accounts under "Settings".
Select Google Ads.
The last step depends on whether you are linking your own Google Ads account or not:
If it's your own account, then under “Your Google Ads account,” find the Google Ads customer ID of the account you want to link. You can find the customer ID at the top of any Google Ads page when you're signed in, near your email address. Click Link under "Actions".
If it's another account, under “Other Google Ads accounts,” click Link account and enter the Google Ads customer ID of the account you want to link.
Keep in mind that you can find the customer ID at the top of any Google Ads page when you're signed in, near your email address. Click Send link request.
Approve link request in Google Ads
Sign in to your Google Ads account.
Click the tools icon in the upper right corner of your account.
Click Linked accounts.
Under “Your linked accounts and products", find "Google Merchant Center”, then click Details.
Find the account you want to link. The “Status” column will say “Needs your approval.” Click View request in the “Actions” column and review the request details.
To approve the link, click Approve. To reject this link, click Reject. If you want to link these accounts later, a new link request will need to be sent from Merchant Center.
After requesting Google Ads and Merchant Center accounts to be linked and approving the request, you're good to go and set up your Google Shopping.
For more details, check out this article on linking the Merchant Center and Google Accounts.