you need sun to dry it. you could lightly apply a hair dryer too. but you will also find size and mould treatment glues in your hardware/wallpaper places. but my guess is that you began the item and completed it all in one go. it is usually better to do two or three layers...let it dry -- and do another couple -- depending on the strength and layers you want.
mache is remarkably slow drying in humid weather and will take up mould especially with "untreated" pastes.it is also a problem that with some construction designs you will encourage the mache to standardly dry from the OUTSIDE IN. this means that when the outer layer's dry it creates a seal against the moisture still trapped beneath. thus you can get moulds and weak structures.

this is why i gave up using mache here in sub tropical brisbane as the drying factor was so difficult with the persistent humidity (but I'm back exploring it).

with most pieces it is best to suspend them so the air get underneath the item -- and when you can peel away any cling wrap of other moisture  barrier's you may be using. ovne grils are ahndy for thsi puprose but don;t suspend an itm by hooks as it will go out of shape and stay that way. similarly as soon as you have a reasonable hard casing it is sometmes better to pull out any stuffing you may have used (like scrunched up newspaper) which will act as a reservoir for moisture and protect the item from circulating dry  air. This is why i like covering any mould i use with cling wrap -- thatw ay i know where the mache ends and the mould begins and i know that their compoenents --esp the water -- won't mix.

but with mache and layers -- less is best. especially when you come to pulpy things too -- keep the moisture level down as much as you can. when you have laminated a piece with a layer of paper --always wipe off the excess paste. this is why i always use my hands and only use a brush occasionally. i even massage the strips into place and may even squeeze them from underneath to block them into shape and reduce their moisture content.

but if it's  bad mould and internally generated-- i'd start again - if you immediate remedies don't work

you can get fungicide in the paste but it will react with your hands. similarly a dryer method is to use PVA glue which in a 3:1 solution and a faster drying time -- will dry more consitently than cellulose pastes. it gives a laminating effect too. but pva has its own challenging aspects -- and mould isn't usually a problem.

dave riley