Which model number, there are two with similar names.
If it is 73743, that model is now officially supported, it should pair right out of the box as long as you did the reset correctly. So just contact support and they should be able to help you.
https://www.amazon.com/SYLVANIA-Smart-Dimming-Switch-Formerly/dp/B0196M620Y
https://support.smartthings.com/hc/en-us/articles/115000236823-SYLVANIA-Dimming-Switch
If it’s the square switch instead, that’s being sold only in Europe, doesn’t yet have an official integration, and only a few community members have tried it. Ask in the following thread
https://www.amazon.de/gp/product/B00YSXBROI/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
( also, please don’t post questions about individual devices to the buttons FAQ thread. Ask them in the individual device threads instead. Otherwise the FAQ thread becomes too hard to use. Thanks.)