Here is the most common source of confusion. Unlike Wi-Fi cards, most USB Bluetooth dongles rely on the chipset manufacturer for drivers, not the brand (UGREEN).
For Linux users wanting the top driver config: driver ugreen bluetooth 53 top
sudo apt update
sudo apt install bluetooth bluez bluez-tools rfkill
sudo modprobe btusb
sudo systemctl enable bluetooth
After this, the UGREEN 5.3 adapter will appear in your Bluetooth manager. Here is the most common source of confusion
If automatic fails, or you want the absolute latest features, do this: After this, the UGREEN 5