The connection to Google works when someone leaves a 4 or 5* review, see the process below to assist with explaining to employers and candidates prior to them leaving you a review:

1) Client/candidate (Reviewer) leaves a 4 star review or higher on Sourcr.

2) Reviewer submits the forms and a redirection page pops up as below:

3) After the 7 seconds elapses, your Google review form is displayed and the text has been copied to the clipboard for the reviewer.

4) The reviewer needs to sign into their g-suite account and submit the review.

We don't see a 100% conversion as Google requires reviewers to have a Google account. We've set it up in a way that it auto displays the form and makes it easy to submit, however the requirements of a Google account is restricted by Google themselves. As a percentage, we see around 75% of reviews from Sourcr that reflects on to Google.
Check this article regarding Google My Business Troubleshooting. You can also test your GMB integration with the link provided inside: Google My Business - Troubleshooting Guide