How much should I charge for exhibiting an art installation?

seems like a question that should be answered based on context.

is the exhibit at a private/independent institution with funding of its own, or part of a larger institution such as a university or civic arts center?

will they insure, or pay for replacements of 'mac,soundcard,speakers' in case of accidents or even normal wear and tear?

how often will you need to go in to maintain the installation? (how many hours will you spend attending to it, even if its already done?)

depending on these questions, you might ask for more or less.

(my initial guess on some monetary amount though for what you've described so far, could be anywhere between $500 to $2000 USD - if they will insure/replace the equipment, and you never have to go in to attend to it once it's setup, plus the venue is small or not well-funded, you could charge much less, though... sometimes this decision can be based on whether you want to be more inviting to repeat the experience later, then you could present it to them differently: they could even buy the equipment themselves, and then pay you just an hourly wage that you'd decide is fair for your time, which could extend to other projects utilizing the same equipment, etc.)

there are many different contexts to consider here(even locality: is the arts scene competitive and booming there, or does it require help in growing? if it is small and struggling, then you'd want to charge less in hopes of longer-term benefit to the place at large). i'd also ask the artists in your local area.

just my 2cents(i've only done 2 installations, both in a single museum exhibit to demonstrate basic ideas about music-theory to children... i did not have to setup equipment or go into the museum at all, just make max patches and send them to the manager of the project by email... by the end of the project, i ended up making $400 for 2 max patches(but this wasn't a price i decided on, the max patches were easy for me and when they mentioned the price i just accepted because it was one of my first gigs using Max... i'd say i'm still pretty pleased by that experience)... however, this was in Spokane, WA, USA back around 2011... and times have changed, plus, i don't know the scene in Belgium -> sometimes, to uphold a good reputation and a fair economy for all artists local to the scene, you don't want to charge too little, either, so i'd ask artists who are local to that area, too, if you can).

i've not much experience, and payment for max work is always a difficult question to answer(since the contexts stretch far and wide), hope this can help, though.

best of luck!