The SD card goes into the chime from the same side where the SET button locates.
After inserting the SD card, you may need to format the SD card in the app to get it ready for the WUUK device. (How to format the SD card: https://wuuklabs.zendesk.com/knowledge/articles/900000824643/en-us?brand_id=360002883711)
Dashboard -> the Gear icon next to your doorbell's name-SD card
Please note that the WUUK Smart Doorbell can only take an SD card no larger than 64GB.