Hi @sweetapp21,
It seems to be a weird issue somewhere in between Adalo and Integromat.
I can confirm that “Add Record” module, connected to “Users” collection, doesn’t work properly - same result as yours.
However, the record is added to Users collection.
I’ve checked same request in Postman and in regular HTTP Integromat module - records are added successfully.
So, as a workaround, you can use HTTP call to create user record.
I’ve submitted a bug to Integromat - will see what they answer. But I’m afraid this will be a ping-pong game between the support of 2 companies. Hopefully I’m wrong 
Best regards, Victor.