Invalid credentials - Magento 2 and Webgility Online
If you are getting this error while testing the store connection in Webgility it means the user isn’t entering the correct store admin details on the store connection screen.
1). Login to Magento 2, and edit the Integrated user that you have created for Webgility
2). Reauthorize the Access Token for the user that is created for Webgility. Go to Admin> System> Integration.
3). Copy the Access Token and click Done.
4). Go to Settings> Connections.
5). Click on Edit> Update Credentials to test the store connection for the Magento store.
6). Enter the correct store URL in the “Your Store Web Address” field in the store connection screen, then click Continue.
7). Enter the server details and FTP credentials, which will be provided by your system administrator or your hosting company. Click “Connect to Store.”
8). Enter the store module URL and the store admin username and password, then click on "Connect to Store.”
Note: Please enter a valid store admin username and password. Other user credentials will not work, as other users don’t have admin privileges.
If it’s still not working and giving the same error message, then I would suggest logging into the Magento store on a browser with the admin credentials to check whether the credentials are correct or not. Then enter the store admin credentials in the connection screen, then click "Connect to Store.”
9). If you are still getting the same error, whitelist the below IPs and then check the Store Connection again.