It looks like a friction fit. The thickness of the stiffener on the flex PCB suggests that the board edge connector is actually a 180 angle180deg card edge connector, which also suggests friction fit. The size looks like it's for a 20-30mil FR4 stiffener (be nice to check the thickness).
The notch (enforced by the PCB) ensures that the connector is keyed.
This looks like an older/chinese connector or a custom connector, it's not one made by a manufacturer. You might be able to match the pitch and the card thickness with a different connector but it wouldn't be a 180deg connector.