The integrator name is a header value with a length limit
The Pasaj setup has three fields, and the first differs from the others: the integrator name. It is not a credential but an identifier attached to requests, limited to 30 alphanumeric characters. If you are building your own integration, writing SelfIntegration here is the established convention. Entering a long company name and exceeding the limit produces an error that is hard to spot during setup.
The key and secret sit in the Pasaj seller panel under account information → integration information.