In order to ensure that participants only use a compatible device when taking your study, you first need to make sure that you have clearly specified what devices are compatible in your study description, and also indicated this by using the options on the study setup screen. Please see here for more information.
If you have done this but you are still receiving submissions on incompatible devices, submissions from participants who take part using an unsupported device do not require approval. What we mean by this is that you are under no obligation to pay for submissions from incompatible devices. Instead, you should message the participant(s) to request that they return their submissions voluntarily (and explain the reason why). If you do not hear back from the participant(s) within 5 days, contact Support via the button below