A lot of good recommendations here, but I think some of them miss what is likely the problem. A lot of restaurants use a machine like that; it can make good coffee. As Tim Post suggested, it should be serviced once in a while.
There's nothing wrong with fresh Maxwell House Original Roast coffee. It's popular for a reason, and many restaurants use it.
Taste the tap water you're putting in. If it tastes good to drink, and doesn't have any weird smells or taste, it should be fine for making good tasting coffee. If you wouldn't want to drink it, try bottled water that tastes good to you for making the coffee.
Most paper coffee filters should be fine. Satisfy your curiosity by brewing three nested filters with no coffee and about one cup of water. That will produce a much stronger concentration of any paper flavor you would get in normal brewing. With some cheap filters, you might notice a paper taste if that's the only thing adding flavor. But unless it produces a strong off-flavor, it will be overwhelmed by the coffee flavor unless you have a very discerning palate.
If the machine is clean and the water is good, the two most likely culprits for coffee that tastes like burnt water is stale coffee and too little grounds.
A big canister of ground coffee smells and tastes great when you first open it, but it degrades very quickly. Within a few days, very little of that great aroma will be there when you open the canister, and by the end of a week, what aroma there is will be of grounds that have started to oxidize. At least buy coffee in a canister size that the office can go through in a few days. Restaurants use prepackaged coffee pouches (including Maxwell House). It isn't just for portion control and to save employee time. The pouch is opened and then used immediately, so the coffee is like when you first open the canister.
The amount of coffee is a common source of weak flavor. People often use way too little coffee. It will be more expensive to buy the coffee pouches, but if you do, and buy the appropriate size (they are sized for different machine capacities), the pouch will provide an appropriate amount of fresh coffee. If you spoon out ground coffee from a canister, target the industry standard 16:1 water to coffee ratio.
Coffee scoops are typically either one or two tablespoons. A level measure will be about 5 grams per tablespoon. The markings on the carafes are usually either 5 fl oz or 6 fl oz cups. For easy calculation, figure 30 grams per fl oz of water, so 150 or 180 grams of water per marked cup. At a 16:1 ratio, that's roughly two level or rounded tablespoons of coffee per marked cup. People often use one tablespoon per marked cup, which produces watery coffee.
Another source of the burnt flavor is making more coffee than can be consumed within about half an hour, then keeping the carafe warm on the built-in hotplate. If you are measuring your own grounds, you don't need to make a full carafe at a time if that's more coffee than the office can quickly consume.