Software and Manual:

https://sikaicase.com/blogs/support/setting-for-software

macOS:

Command=Win, Option=Alt, Control=Ctrl.

② "Sleep" Mode of BT version

The BT version keyboard will automatically enter the “sleep’' mode if there is no operation for 15 minutes for saving power. The keyboard won't respond in "sleep" mode.

Press key "1" can wake up the keyboard to enter the "work" mode, which takes about 2 seconds to complete, and automatically connect.

New Version have could enter max 18 characters one key.