Graduate / What are the differences of these MFA admission requirements? [4]

No specific motivation letter requirements. What to do?

Hi, I am currently writing a motivation letter for Master's degree admission. The school I'm applying to does not provide any specific requirements about how the motivation letter should be written (format, shrift, etc.), it is only stated it should be about 300 words. What should I do in that case, there should be some standard specifics I must be aware of after all?