Many court web sites have prominent references to "mandatory" electronic filing or "mandatory ECF." Do not be alarmed. You are not required to file electronically, unless you are an attorney.
It is true that, in most courts, attorneys must now file all documents and forms electronically, and they must take training on how to file electronically with the court. However, by law, that rule does not apply to individuals filing without the help of an attorney. If a court clerk tells you otherwise, they are incorrect. Ask to talk to their supervisor to clear up the matter.
In most cases filing electronically is not all that technologically challenging. In many districts, it simply means filing the documents in PDF format.