Client-side encryption is only required on the eWAY Rapid payment processor. If client-side encryption is not setup on eWAY rapid, users may experience an error when attempting payment.

To setup regular eWay accounts on NationBuilder, you should only need your eWAY Customer ID* and Refund password. 

Relevant:

Client-side encryption for eWAY Rapid

Transaction Response Codes for eWay