If a form is sent to a user via notification or communication, and they click the link and receive a message that says "You do not have access to this form", here is something you can check:

1. Open the placement group in which the form was assigned
2. On the Details page, ensure "Allocations finalized to..." each role is ticked

Without the above setting, the role indicated does not know about the placement(s) they connected to, including any forms assigned with the placement context. It is important to tick those boxes by the time the placements start so that everyone can have visibility on what they need to know or do.