RushFilres requires an SSL certificate on the server(s) to work.
Order a * certificate (wildcard certificate), there will be several servers on an ongoing basis (scaling) so it's best not to have a "named server certificate".
The SSL certificate is used to encrypt the data traffic between the servers and the clients. Therefor you don't need an EV certificate for this.
We recommend using 2048-bit encryption.
If you don’t have a SSL provider, we can recommend The SSL store. https://www.thesslstore.eu/rapidssl/rapidssl-wildcard.aspx
or we can order it for you at a price of 150€