This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
糩 combines 米 (rice) with 會, which likely contributes the sound. The exact historical development is uncertain.
With 米 (rice) on the left and 會 on the right, picture a meeting where rice is served, but the kanji's meaning remains obscure.
For カイ, imagine a meeting (会, カイ) about rice: 会 -> カイ, and the rice component 米 hints at the kanji's grain-related shape.