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Hey there!
First I’d like to welcome you to the Postman community and congrats on getting started on your 30 days journey! 
So the error we are seeing here is “We could not find the collection you are looking for”
When submitting a solution, we need to pass a valid collection id in the params part of the URL (This is what {{collection_uid}} is)
What I’d suggest is setting a collection variable (with that same name) and setting it to the collection uid that you are trying to submit.
The UID can be found on the right side of the page near the documentation section (under ‘info’)
