It’s different on a communal level. For plastics there ist either a yellow bin or the yellow bag which can be requested by the local Abfallwirtschaftsverband. If you have the yellow bin, just place plastics in there loosely. You could use any plastic bag then.
For paper there is typically a blue bin. All paper goes in there. Whether loosely or in any paper bag die not matter, but it has to be paper only.
Black bin “Restmüll” also loose, or any kind of bag you like to use.
Compost: typically “compostible” bags are not suited, paperbags are ideal. The compostible bags in most cases take too long to rot and have to be separated manually in the compostation facility.
Reese’s You are able to get them in Germany, but only in miniscule portions.