merging audio files

[Appletise]

so frustrating, l have followed the instructions for audacity, online and have successfully merged the m4a files into one track, however when I try to export it as mp3 , m4a. it doesnt allow, saying l have to download LAME. when l click download it takes me to website as attached, and says in MAC it is already built into Audacity :x
l can export as an aiff file but that takes up many times the space, where an mp3 or m4a would be sufficient. are there any other audio formats that can be tried? please help me get this audio mergering done, btw tried quicktime and trying to drop a 2nd m4a file onto the 1st m4a quicktime window did not work, although mp4s merging was no problem.
thanks

 

[Stephen.R]

It’s not the most straight forward solution but you could just export to aiff and then convert it to m4a/mp3 using either QuickTime or iTunes.

 

[Pakaku]

Similarly you could try exporting to FLAC, and then use something like XLD to convert that into an M4A