The shop you're applying for is a SASSIE mystery shop, not a Presto Insta-Shop. SASSIE mystery shops appear on the Presto map as orange pins. They different software that's located on a different system (so you need a login there), and they are mostly assigned by schedulers, not self-assigned.
If you see a SASSIE shop on the Presto Map and you want to apply for it, click the pin for the shop details, then click the Apply button in the details:
This opens the mystery shopping company's login page in a new tab or window. If you don't already have an account on that mystery shopping company's system, you can create one here. You should address any questions about the shop, shop assignment, or any other shop details to the scheduler on that system, whose contact information should be available on the shop listing on SASSIE.
To apply for a SASSIE shop, you must log on to the mystery shopping company's SASSIE system, not on the Presto map.