Streaming stick plus works fine on a non-4K set, I'm using one myself. It's just a matter of setting the Roku to your tv's resolution.
The stick only provides video and audio to the tv via an HDMI connection, so do you really mean your set has no HDMI ports -- or maybe you mean you are plugged directly into the tv's HDMI port, not by using an HDMI cable between them?
Error 020 indicates that the communication between the Roku and tv has failed to establish the required high definition copy protection (one more acronym, HDCP) protocols that are required for high definition television over the HDMI link. The problem could be at either end.
A really old tv set may not have the required protocols built in (unlikely), or not functioning properly.
Or your Roku may be defective.
Or perhaps it is not making a good HDMI connection. Make sure the stick is firmly inserted in the tv's HDMI port, and make sure the connectors on both are clean by blowing them out with compressed air.
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