Starting from 2.2.1 release, Remote Files SE can work as HTTP (default) or HTTPS server. Choosing between these modes may depend on kind of task, the program is solving.

Thus, the server does not encrypt traffic in HTTP mode. Therefore, it does not require certificate and uses less CPU resources. No certificate error messages (see later) rise in browsers. This mode may be useful to create corporate file servers that provide authorized separate access to no confidential information to employees or clients. In HTTP mode there is a very little risk to intercept information, so take it to consideration. If small possibility to loose data is not dangerous, this may be the best choice.
A risk to intercept information in HTTPS mode, as stated, equals to zero due to traffic encryption. The server uses much more CPU time to encrypt/decrypt traffic, but this may be of no importance.

The server requires server certificate in HTTPS mode for normal work. Remote Files SE may create certificate itself or use a third-party certificate. In the case when certificate is self-generated, web browsers show certificate error message each time a user connects to the server. This is because the program cannot sign certificate (this process is not automatic and requires annual fees for every user of Remote Files SE). This message may disappear with a third-party certificate, but if necessity to accept certificate when a user connects to server is not suitable, changing server mode to HTTP will help.