Urgent issue while publishing ojs 3.1.1.0

We are using 3.1.1.0 version of ojs and recently installed it. I am publishing a journal named International Journal of Microbiology and Immunology using this platform but stuck at Public galley identifier. I really don’t know what is it expecting from us? Please help and mail the solution to me .

Also tell me what is Identifiers.

What is API Keys? Is it important or not?

Early response is awaited.