I found info on this place in the Rick Steves guidebook and had a delightful evening with delicious food (and cheap!) The communal meal is set up in a former church/current community center. You sit at long tables with other people and the food is served family- style (something like summer camp!) My tablemates included two other Americans, an Australian man with his adult daughter, a Chinese woman studying in Denmark, and a Danish man. So interesting. It was a really enjoyable evening, in a neighborhood away from the tourists. The food was delicious! They also sell inexpensive food earlier in the day. You could even eat there more than once. The Chinese woman said she comes there “all the time.” They have other activities on their schedule as well, but I didn’t experience any of them.
I was staying not far from Nyhaven and took the subway there, getting off at Enghave Plads. (Don’t mix this stop up with Enghave Brygge.) The subway is pretty easy to navigate and your guide should be able to help you figure it out. Once I got off the subway, I had to get oriented to walk a few blocks to the Folkehuset. The neighborhood seemed lively and safe, but not so touristy. You could of course take an Uber or whatever if you preferred.