You can work from the listen server in pure blueprint without a source build totally fine! I just recommend being able to use C++ for dedicated server based multiplayer projects. Technically you can do the same with the dedicated server, but will need a bit of a C++ tutorial getting the environment ready to go and building.
You can totally build it with the listen server, and if you wanted to set up dedicated servers later if you get some playerbase and it takes off, totally possible, would just take a bit of porting.