The Aeotec Multisensor 6 will, by default, report hourly. It can be configured to report more frequently, or to report on threshold changes (e.g. when humidity changes by more than 10%).
However, also by default, when configuring a shorter reporting interval, the device will use a minimum of 60 minutes when it is operating on batteries; if running from USB power it will honour a shorter reporting interval (e.g. 1 minute, 30 seconds, etc.). The device’s technical documentation explains how a four minute reporting interval can be achieved on batteries by changing the device’s wake-up interval, but you need to be aware that these limitations exist for a reason - i.e. maintaining reasonable battery life.
For your use-case, I would suggest exploring the device’s threshold reporting capabilities, rather than attempting to increase the reporting interval. This would allow you to control your fan as required as the humidity rises above a trigger threshold and then falls back below a recovery threshold, without incurring excessive battery consumption from frequent reporting of unimportant (for this use-case) intermediate values, etc.