I've had clients and prospective clients come to me with this problem recently. They set up their Google Ad Campaign and set their desired cost per acquisition (CPA) using the Target CPA (tCPA) bid strategy, now they figured it was just a matter of kicking back to watch all of the leads come pouring in.
As many have discovered, it's not that easy. You see, tCPA is considered an automated bidding strategy that leverages Google's machine learning algorithms. If you start off a new campaign with this type of bid strategy, especially with your tCPA set too low, it's very common to see low ad impressions.
I personally like to start off my campaigns using Manual CPC or Maximize Clicks bid strategy. Once the campaign starts generating conversion data, Google's machine learning algorithm will start to learn which visitors are more likely to result in a conversion.
At that point, I then experiment with more automated bid strategies like tCPA, Maximize Conversions, and Target Return On Ad Spend (tROAS) if you're able to track sales revenue with your campaign.
If you're still experiencing low ad impressions, it may be because you're starting your campaign with match types that are too conservative and barely have any search volume.
Or your overall bid is just too low for the keywords you're bidding on.