Understood. Well there's two ways to attack this and both aren't simple.
1) Using the image that comes with the board, find an appropriate cross-compiler then download the lftp source code and cross compile it and put it on your board.
lftp is available as part of the Yocto project https://layers.openembedded.org/layerindex/recipe/191917/ and there is a link inside that to the actual code repo. You'd need to match the lftp version to suit your board.
The cross compiler can be found in a few places, I use Yocto and that offers the extraction of an SDK which contains the compilers and lots of other dependencies matched to the image I'm working on. The challenge might be matching one to your board if you need to compile against source and libraries etc.
Once you have both is a matter of cross compiling lftp and getting on your board....
* If you are actually just trying to get some files on the board for eval purposes (thinking ftp was the way to go) you could use scp (like ssh but sends a file) or mount a USB stick with your files on it.
2) This option is to build a complete image yourself from scratch and put that on your board. Chances are you will have to do this eventually anyway. If you choose the Yocto build system you can simply include lftp in your local.conf and build the image; Yocto does the rest, pulls in all the source files, builds everything you need to run a board compatible image (you may have to include the .bb file in the link above).
Once the image is built pop it on a SD card or use UUU for downloading onto the actual board. Going down this route you have full control of the build and you can also extract the SDK for future out-of-tree builds if required. Set it up before leaving the office and let it build over night.
Document how to do it all: https://www.nxp.com/docs/en/user-guide/IMX_YOCTO_PROJECT_USERS_GUIDE.pdf
Hope it helps..
