Each team should demonstrate the delivered work to the client at the end of a week. Then the client can accept that week so that the team gets paid.
The details of the review are not mandated by Squads, but we coach teams and clients if needed. The best way we've found is to agree on a well defined business goal at the beginning, and show how this goal is reached during a quick high level demo of the features.
Let us know if you feel your reviews aren't running well, we're here to help.