How to control Plug and Play on UR20?

The bolt pattern is different between a UR20 and the other UR robot. 

UR supplied with the robot an adapter plate to convert the bolt pattern of the robot to a normal bolt pattern: 50mm PCD 4 x M6 screws. 

So you can order a normal kit for UR, it will fit with the UR20 with the Adaptor plate UR. 

If you don't find the adaptor plate, you can order another adaptor plate: ACC-APL-UR20.