I tried reserving the sandbox but was not able to use it. I was following the lab and the first thing it says is to log in with admin credentials and create an api user. I don't have admin credentials. I tried the ones sent to me but they are not admin credentials. I also tried the default admin/Admin123 but that did not work either.
I then tried going to fmcrestapisandbox.cisco.com/api/api-explorer/ and I got an error message saying forbidden.