This was a pain for me to figure out too. You need to (2) datasets to accomplish this.
One dataset is connected to your dynamic page (client collection). The other is connected to your repeater (offers collection).
The offers dataset needs to have a filter on it that points to the multi-reference field shared by the client and offer collections.
Here’s an article from Wix that explains it in detail:
Once connected, the repeater will only show offers for that particular client.