See https://dev.mysql.com/doc/refman/5.7/en/privileges-provided.html#priv_create-temporary-tables
Since Matomo 3.12 it seems this new permission is needed. Not sure if we somewhere document needed permissions? Would either need to add it, or document the list in general.

AFAIK this requirements are needed at least

• CREATE, DELETE, DROP, INSERT, SELECT, UPDATE, LOCK TABLES, CREATE TEMPORARY TABLES, ALTER, INDEX