It's essentially a credit-based Azure subscription. It's not something you can request - it's granted by Microsoft based on the company's own discretion/rules - including Microsoft training courses. In particular, they are distributed to students and MCTs when they access hands-on labs via one of the Authorized Lab hosters (ALH’s). More at https://learn.microsoft.com/en-us/credentials/certifications/mocazurepass
If the above response helps answer your question, remember to "Accept Answer" so that others in the community facing similar issues can easily find the solution. Your contribution is highly appreciated.
hth
Marcin