The Xiaofang T20L is different from the T20, which requires some more steps to get the CFW running from SD card.
The cfw-1.0 bootloader used on the T20 is compatible with the T20L. So follow the installation instructions for installation of the bootloader (this is the first part of the installation instruction).
There is an additional step required for the T20L. First, clone the repository from github. If you are on Windows download the repository as zip file. Make sure nothing gets windows line endings.
Inside the firmware_mod folder, there are two files called uEnv.bootfromnand.txt and uEnv.bootfromsdcard.txt. Delete those files and rename the
uEnv.bootfromnand.t20l.txt to uEnv.bootfromnand.txt and uEnv.bootfromsdcard.t20l.txt to uEnv.bootfromsdcard.txt. Effectively, you replace the
existing uEnv files with the two modified specifically for the T20L.
Next, inside the firmware_mod folder, there is a driver folder and a driver_t20l folder. Copy all files from driver_t20l and copy those into the
driver folder. Make sure to overwrite any existing file to replace them with the proper drivers.
Now you can continue with step 2 from the firmware installation instructions by copying the contents to the SD card and further following the instructions.