How to sign "must" in American Sign Language:
Definition: To be obliged to; to be required or compelled to.
Pronunciation (sign description): Dominant clawed forefinger (handshape) held in space (location), palm down (palm orientation), moves downwards once at the wrist with a strong intonation (movement) with the mouth morpheme (NMS).
ASL Learner Tip: Not to be confused with SHOULD, HAVE-TO (kind of more euphemism than MUST).
Language play is often used by Deaf signers.
Inflection and language play: The meaning of this ASL sign is the same except that it's five times MUST. That is, absolutely must.
Another context in capture (April 2020): Marcus Bryant signed MUST, double-MUST, 5x-MUST when talking about wearing a mask as absolutely required for himself before entering a chain store.
The technique of this language play is the same true for REQUIRED.
First 100 words.
As you feel more comfortable with the first few hundreds of ASL signs, progress further with your vocabulary and learn signing more.