Ok. Installed the updates and followed your instructions, I did get some errors, which might lead to the answer?
jafet-HP15:~/Downloads/20201202_LINUX_BT_DRIVER$ sudo make install INTERFACE=usb
[sudo] password for jafetalcocer:
Sorry, try again.
[sudo] password for jafetalcocer:
mkdir -p /lib/modules/5.8.0-53-generic/kernel/drivers/bluetooth
Start Realtek Bluetooth USB driver installation
mkdir -p /lib/firmware
Copy rtkbt-firmware/lib/firmware/rtl*_fw to /lib/firmware
cp -a rtkbt-firmware/lib/firmware/rtl*_fw /lib/firmware
Copy rtkbt-firmware/lib/firmware/rtl*_config /lib/firmware
cp -a rtkbt-firmware/lib/firmware/rtl*_config /lib/firmware
make -C usb install
make[1]: Entering directory '/home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb'
rmmod btusb
rmmod: ERROR: Module btusb is not currently loaded
make[1]: [Makefile:7: install] Error 1 (ignored)
mv /lib/modules/5.8.0-53-generic/kernel/drivers/bluetooth/btusb.ko /lib/modules/5.8.0-53-generic/kernel/drivers/bluetooth/btusb_bak
mv: cannot stat '/lib/modules/5.8.0-53-generic/kernel/drivers/bluetooth/btusb.ko': No such file or directory
make[1]: [Makefile:8: install] Error 1 (ignored)
rmmod rtk_btusb
make -C ./bluetooth_usb_driver
make[2]: Entering directory '/home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver'
make -C /lib/modules/5.8.0-53-generic/build M=/home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver modules
make[3]: Entering directory '/usr/src/linux-headers-5.8.0-53-generic'
CC [M] /home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver/rtk_coex.o
CC [M] /home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver/rtk_misc.o
CC [M] /home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver/rtk_bt.o
LD [M] /home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver/rtk_btusb.o
MODPOST /home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver/Module.symvers
CC [M] /home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver/rtk_btusb.mod.o
LD [M] /home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver/rtk_btusb.ko
make[3]: Leaving directory '/usr/src/linux-headers-5.8.0-53-generic'
make[2]: Leaving directory '/home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver'
cp -f ./bluetooth_usb_driver/rtk_btusb.ko /lib/modules/5.8.0-53-generic/kernel/drivers/bluetooth/rtk_btusb.ko
depmod -a 5.8.0-53-generic
make -C ./bluetooth_usb_driver clean
make[2]: Entering directory '/home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver'
rm -rf *.o *.mod.c *.mod.o *.ko *.symvers *.order *.a
make[2]: Leaving directory '/home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb/bluetooth_usb_driver'
echo "install rtk_btusb success!"
install rtk_btusb success!
make[1]: Leaving directory '/home/jafetalcocer/Downloads/20201202_LINUX_BT_DRIVER/usb'
jafetalcocer@jafet-HP15:~/Downloads/20201202_LINUX_BT_DRIVER$
Please note these errors
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rmmod btusb
rmmod: ERROR: Module btusb is not currently loaded
make[1]: [Makefile:7: install] Error 1 (ignored)
mv /lib/modules/5.8.0-53-generic/kernel/drivers/bluetooth/btusb.ko /lib/modules/5.8.0-53-generic/kernel/drivers/bluetooth/btusb_bak
mv: cannot stat '/lib/modules/5.8.0-53-generic/kernel/drivers/bluetooth/btusb.ko': No such file or directory
make[1]: [Makefile:8: install] Error 1 (ignored)
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