m0useanswered grow question a year ago Place the air conditioner in the room and shut the door if its a mobile unit, close the blinds and shut the windows and other vents.
AC cools the air and removes excess humidity. If you can get that room down to 22-24c the RH should drop down with it.
Running a dehumidifier in the same space as AC will cause the temps to spike as they generate heat thus making the AC unit work harder.
If your AC unit can't keep up it might be low in refrigerant or the radiator coils need cleaning as they can't dissipate the heat.
If the RH outside is 89% you might just be fucked till it lowers a bit or you can manage your environment better/ fix the ac unit. I have a feeling your tent or the room it is in is drafty and that's where all the cool dry air from the AC is escaping from. Keep air flow going in the tent though, turn on exhaust fan on low or a fan blowing into a wall of the tent moving air but not directly pointed at the buds. Stale air is not good.
A fan alone with not lower RH it just moves the air and adds minute amounts of heat from the motors moving parts. If the air its moving is also high in RH it does not just magically disappear. Granted homes with bad air flow can trap heat and RH if they are stuffy and cramped.
Good Luck!