Complete noob here, what does it mean to compile manually?

Basically I’m trying to run this

https://github.com/andjoer/AI_color_grade_lut/blob/master/64pix2pix.ipynb

everthing works fine but it gives me this warning at the end :

WARNING:tensorflow:Compiled the loaded model, but the compiled metrics have yet to be built. model.compile_metrics will be empty until you train or evaluate the model.

Then I run this:

https://github.com/andjoer/AI_color_grade_lut/blob/master/Pix2LUT.ipynb

Same thing everything works but at the end I get this:

WARNING:tensorflow:No training configuration found in the save file, so the model was not compiled. Compile it manually.

What can I do to get rid of this problem?